Pub Date : 2024-08-29DOI: 10.1103/physrevapplied.22.l021002
Shuanghai Wang, Kun He, Yongkang Xu, Zhuoyi Li, Jin Wang, Caitao Li, Xingze Dai, Jun Du, Yong-Lei Wang, Ronghua Liu, Xianyang Lu, Yongbing Xu, Liang He
In recent years, spin-orbit torque (SOT) generated by heavy metal (HM) has garnered increasing attention. However, SOT-magnetic random-access memory based on HM suffers from a low spin Hall angle and high current density. Here, we demonstrate that the critical switching-current density () in a multilayer structure of has been reduced by 79% compared with that of , achieving a value of 5.88 × . This value is considerably low among all reported values in the system literature. The reduction of is accompanied by enhanced dampinglike torque efficiency () and reduced coercive force (). A perfect linear correlation has been observed between and /, which supports the domain-wall depinning model of the SOT-induced magnetization reversal in this system. Crucially, this linearity extends to several metal dopants possessing the identical superlattice structure. This research offers insights into the future of low-power, high-density magnetic memory technology based on HM materials.
近年来，重金属（HM）产生的自旋轨道力矩（SOT）越来越受到关注。然而，基于重金属的 SOT 磁性随机存取存储器存在自旋霍尔角低和电流密度高的问题。在这里，我们证明了 Ta/(Pt/Ta)4/Pt/Co/Ta 多层结构中的临界开关电流密度 (Ic) 与 Ta/Pt/Co/Ta 相比降低了 79%，达到了 5.88 × 106A/cm2。在 Pt/Co 系统的所有文献报道值中，该值是相当低的。Ic 值的降低伴随着阻尼扭矩效率（βD）的提高和矫顽力（Hc）的降低。在 Ic 和 Hc/βD 之间观察到了完美的线性关系，这支持了该系统中 SOT 诱导磁化反转的畴壁衰减模型。最重要的是，这种线性关系延伸到具有相同超晶格结构的几种金属掺杂物。这项研究为未来基于 HM 材料的低功耗、高密度磁存储器技术提供了启示。
{"title":"Lower switching-current density in Ta/(Pt/X)n/Pt/Co/Ta (X = Ta,Mn,Cu,V,Zr, Bi; n = 3, 4) multilayers based on a domain-wall-depinning model","authors":"Shuanghai Wang, Kun He, Yongkang Xu, Zhuoyi Li, Jin Wang, Caitao Li, Xingze Dai, Jun Du, Yong-Lei Wang, Ronghua Liu, Xianyang Lu, Yongbing Xu, Liang He","doi":"10.1103/physrevapplied.22.l021002","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.l021002","url":null,"abstract":"In recent years, spin-orbit torque (SOT) generated by heavy metal (HM) has garnered increasing attention. However, SOT-magnetic random-access memory based on HM suffers from a low spin Hall angle and high current density. Here, we demonstrate that the critical switching-current density (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>I</mi><mi>c</mi></msub></math>) in a multilayer structure of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Ta</mi><mo>/</mo><mo stretchy=\"false\">(</mo><mi>Pt</mi><mo>/</mo><mi>Ta</mi><msub><mo stretchy=\"false\">)</mo><mn>4</mn></msub><mo>/</mo><mi>Pt</mi><mo>/</mo><mi>Co</mi><mo>/</mo><mi>Ta</mi></math> has been reduced by 79% compared with that of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Ta</mi><mo>/</mo><mi>Pt</mi><mo>/</mo><mi>Co</mi><mo>/</mo><mi>Ta</mi></math>, achieving a value of 5.88 × <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>6</mn></msup><mspace width=\"0.2em\"></mspace><mrow><mrow><mi mathvariant=\"normal\">A</mi></mrow></mrow><mo>/</mo><msup><mi>cm</mi><mn>2</mn></msup></math>. This value is considerably low among all reported values in the <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Pt</mi><mo>/</mo><mi>Co</mi></math> system literature. The reduction of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>I</mi><mi>c</mi></msub></math> is accompanied by enhanced dampinglike torque efficiency (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>β</mi><mi>D</mi></msub></math>) and reduced coercive force (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mi>c</mi></msub></math>). A perfect linear correlation has been observed between <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>I</mi><mi>c</mi></msub></math> and <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>H</mi><mi>c</mi></msub></math>/<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>β</mi><mi>D</mi></msub></math>, which supports the domain-wall depinning model of the SOT-induced magnetization reversal in this system. Crucially, this linearity extends to several metal dopants possessing the identical superlattice structure. This research offers insights into the future of low-power, high-density magnetic memory technology based on HM materials.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"4 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1103/physrevapplied.22.024070
Chuanxin Zhang, Fei Dai, Xue Jiang, Dean Ta
Acoustic orbital angular momentum (OAM) beams hold potential for underwater communications, particle manipulation, and biomedical applications. However, adapting air-based OAM technologies to the underwater environment presents unique challenges. In the underwater environment, the medium cannot be considered acoustically soft, and commonly used ultrasound frequencies have shorter wavelengths compared with air, necessitating new design approaches. Conventional underwater ultrasonic lens design methods often rely on simplified models that neglect nonlocal interactions and diffraction within the structure, therefore leading to suboptimal performance. We introduce a novel nonlocal inverse design method by integrating the full-wave models with the nondominated sorting genetic algorithm II (NSGA-II). This approach diverges from conventional phase-based design by optimizing the physical structure of the lens to account for nonlocal interactions within the material. We experimentally demonstrate the performance when generating high-purity OAM beams underwater. Our experimental results show that this method can generate high-purity OAM beams underwater, achieving over 90% purity for the OAM beams of topological charges from m = 1 to m = 4. This is a significant improvement compared with traditional methods, which typically reach 70–89% purity. These findings highlight the practical applicability of our method for nonlocally designing the ultrasonic lens, paving the way for advancements in beam performance for various applications.
声轨道角动量（OAM）光束在水下通信、粒子操纵和生物医学应用方面具有潜力。然而，将基于空气的 OAM 技术应用于水下环境面临着独特的挑战。在水下环境中，介质不能被视为声学上的软介质，而且常用的超声波频率与空气相比波长较短，因此必须采用新的设计方法。传统的水下超声透镜设计方法往往依赖于简化模型，忽略了结构内部的非局部相互作用和衍射，因此导致性能不理想。我们通过将全波模型与非支配排序遗传算法 II（NSGA-II）相结合，引入了一种新的非局部反向设计方法。这种方法不同于传统的基于相位的设计，而是通过优化透镜的物理结构来考虑材料内部的非局部相互作用。我们通过实验证明了这种方法在水下产生高纯度 OAM 光束时的性能。实验结果表明，这种方法可以在水下生成高纯度的 OAM 光束，拓扑电荷从 m = 1 到 m = 4 的 OAM 光束纯度超过 90%。与传统方法相比，这是一个重大改进，传统方法的纯度通常为 70%-89%。这些发现凸显了我们非局部设计超声透镜方法的实用性，为提高各种应用的光束性能铺平了道路。
{"title":"Nonlocal inverse design of an ultrasonic lens for underwater manipulation of orbital angular momentum","authors":"Chuanxin Zhang, Fei Dai, Xue Jiang, Dean Ta","doi":"10.1103/physrevapplied.22.024070","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024070","url":null,"abstract":"Acoustic orbital angular momentum (OAM) beams hold potential for underwater communications, particle manipulation, and biomedical applications. However, adapting air-based OAM technologies to the underwater environment presents unique challenges. In the underwater environment, the medium cannot be considered acoustically soft, and commonly used ultrasound frequencies have shorter wavelengths compared with air, necessitating new design approaches. Conventional underwater ultrasonic lens design methods often rely on simplified models that neglect nonlocal interactions and diffraction within the structure, therefore leading to suboptimal performance. We introduce a novel nonlocal inverse design method by integrating the full-wave models with the nondominated sorting genetic algorithm II (NSGA-II). This approach diverges from conventional phase-based design by optimizing the physical structure of the lens to account for nonlocal interactions within the material. We experimentally demonstrate the performance when generating high-purity OAM beams underwater. Our experimental results show that this method can generate high-purity OAM beams underwater, achieving over 90% purity for the OAM beams of topological charges from <i>m</i> = 1 to <i>m</i> = 4. This is a significant improvement compared with traditional methods, which typically reach 70–89% purity. These findings highlight the practical applicability of our method for nonlocally designing the ultrasonic lens, paving the way for advancements in beam performance for various applications.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"313 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-27DOI: 10.1103/physrevapplied.22.024068
Zeferino Ibarra-Borja, Pablo Yepiz-Graciano, Nicolas Claro-Rodríguez, Alfred B. U’Ren, Roberto Ramírez-Alarcón
We report on an experiment in which orbital-angular-momentum (OAM)-entangled photon pairs generated by the spontaneous parametric down-conversion process can be engineered to have particular symmetry properties. Our method is based on the use of a Dove-prism pair in conjunction with Hong-Ou-Mandel (HOM) interferometry resolved in transverse position and OAM. The latter allows us to engineer the postselected two-photon state to exhibit a specific type of symmetry. By selecting particular topological charge values for the pump and for the postselected two-photon state, we can transition from a symmetric two-photon state and a HOM dip to an antisymmetric state and a HOM peak. Spatial resolution allows us to obtain the HOM interferogram both at the single-pixel level and globally by summing over all sensor pixels. Furthermore, through spatially selective OAM projection of the detected photon pairs, we can define multiple transverse regions with different symmetry properties, as verified by our spatially resolved HOM apparatus. Although we used two transverse regions for this proof-of-concept demonstration, this method could in principle be scaled to a larger number of regions, leading to a new technique to be added to the existing toolbox for quantum technologies in the photonic domain.
我们报告了一项实验，在该实验中，通过自发参数下转换过程产生的轨道-角动量（OAM）-纠缠光子对可以被设计成具有特殊的对称特性。我们的方法是将鸽棱镜对与解析横向位置和 OAM 的弘欧芒德（HOM）干涉测量法结合使用。后者允许我们设计后选择的双光子态，使其表现出特定类型的对称性。通过为泵浦和后选双光子态选择特定的拓扑电荷值，我们可以从对称双光子态和 HOM 波峰过渡到非对称态和 HOM 波峰。通过空间分辨率，我们可以获得单像素级的 HOM 干涉图，也可以通过对所有传感器像素求和获得全局的 HOM 干涉图。此外，通过对检测到的光子对进行空间选择性 OAM 投影，我们可以定义出具有不同对称特性的多个横向区域，这一点已通过我们的空间分辨 HOM 仪器得到验证。虽然我们在概念验证演示中使用了两个横向区域，但这种方法原则上可以扩展到更多区域，从而为光子领域量子技术的现有工具箱增添一项新技术。
{"title":"Imaging symmetric and antisymmetric behavior of orbital-angular-momentum-entangled two-photon states","authors":"Zeferino Ibarra-Borja, Pablo Yepiz-Graciano, Nicolas Claro-Rodríguez, Alfred B. U’Ren, Roberto Ramírez-Alarcón","doi":"10.1103/physrevapplied.22.024068","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024068","url":null,"abstract":"We report on an experiment in which orbital-angular-momentum (OAM)-entangled photon pairs generated by the spontaneous parametric down-conversion process can be engineered to have particular symmetry properties. Our method is based on the use of a Dove-prism pair in conjunction with Hong-Ou-Mandel (HOM) interferometry resolved in transverse position and OAM. The latter allows us to engineer the postselected two-photon state to exhibit a specific type of symmetry. By selecting particular topological charge values for the pump and for the postselected two-photon state, we can transition from a symmetric two-photon state and a HOM dip to an antisymmetric state and a HOM peak. Spatial resolution allows us to obtain the HOM interferogram both at the single-pixel level and globally by summing over all sensor pixels. Furthermore, through spatially selective OAM projection of the detected photon pairs, we can define multiple transverse regions with different symmetry properties, as verified by our spatially resolved HOM apparatus. Although we used two transverse regions for this proof-of-concept demonstration, this method could in principle be scaled to a larger number of regions, leading to a new technique to be added to the existing toolbox for quantum technologies in the photonic domain.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"38 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-27DOI: 10.1103/physrevapplied.22.024069
Yaoling Yang, Victor Montenegro, Abolfazl Bayat
Measuring the temperature of a quantum system is an essential task in almost all aspects of quantum technologies. Theoretically, an optimal strategy for thermometry often requires measuring energy, which demands full accessibility over the entire system as well as a complex entangled measurement basis. In this paper, we take a different approach and show that single-qubit sequential measurements in the computational basis not only allow for precise thermometry of a many-body system, but may also achieve precision beyond the thermometry capacity of the probe at equilibrium, given by the Cramér-Rao bound. Thus, using consecutive single-qubit measurements of the probe out of equilibrium is, in most cases, very beneficial, as it achieves lower-temperature uncertainties and avoids demanding energy measurements when compared with probes at thermal equilibrium. To obtain such precision, the time between the two subsequent measurements should be smaller than the thermalization time so that the probe never thermalizes. Therefore, the nonequilibrium dynamics of the system continuously imprint information about temperature in the state of the probe. To demonstrate the generality of our findings, we consider thermometry in both spin chains and the Jaynes-Cummings model.
{"title":"Sequential-measurement thermometry with quantum many-body probes","authors":"Yaoling Yang, Victor Montenegro, Abolfazl Bayat","doi":"10.1103/physrevapplied.22.024069","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024069","url":null,"abstract":"Measuring the temperature of a quantum system is an essential task in almost all aspects of quantum technologies. Theoretically, an optimal strategy for thermometry often requires measuring energy, which demands full accessibility over the entire system as well as a complex entangled measurement basis. In this paper, we take a different approach and show that single-qubit sequential measurements in the computational basis not only allow for precise thermometry of a many-body system, but may also achieve precision beyond the thermometry capacity of the probe at equilibrium, given by the Cramér-Rao bound. Thus, using consecutive single-qubit measurements of the probe out of equilibrium is, in most cases, very beneficial, as it achieves lower-temperature uncertainties and avoids demanding energy measurements when compared with probes at thermal equilibrium. To obtain such precision, the time between the two subsequent measurements should be smaller than the thermalization time so that the probe never thermalizes. Therefore, the nonequilibrium dynamics of the system continuously imprint information about temperature in the state of the probe. To demonstrate the generality of our findings, we consider thermometry in both spin chains and the Jaynes-Cummings model.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"20 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-26DOI: 10.1103/physrevapplied.22.024067
Shreyas Parthasarathy, Maxime Joos, Lillian B. Hughes, Simon A. Meynell, Taylor A. Morrison, J.D. Risner-Jamtgaard, David M. Weld, Kunal Mukherjee, Ania C. Bleszynski Jayich
Many modern-day quantum science experiments rely on high-fidelity measurement of fluorescent signals emitted by the quantum system under study. A pernicious issue encountered when such experiments are conducted near a material interface in vacuum is “laser-induced contamination” (LIC): the gradual accretion of fluorescent contaminants on the surface where a laser is focused. Fluorescence from these contaminants can entirely drown out any signal from, e.g., optically probed color centers in the solid state. Crucially, while LIC appears often in this context, it has not been systematically studied. In this work, we probe the onset and growth rate of LIC for a diamond nitrogen-vacancy center experiment in vacuum, and we correlate the contamination-induced fluorescence intensities to micron-scale physical buildup of contaminant on the diamond surface. Drawing upon similar phenomena previously studied in the space optics community, we use photocatalyzed oxidation of contaminants as a mitigation strategy. We vary the residual oxygen pressure over 9 orders of magnitude and find that LIC growth is inhibited at near-atmospheric oxygen partial pressures, but the growth rate at lower oxygen pressure is nonmonotonic. Finally, we discuss a model for the observed dependence of LIC growth rate on oxygen content and propose methods to extend in situ mitigation of LIC to a wider range of operating pressures.
{"title":"Role of oxygen in laser-induced contamination at diamond-vacuum interfaces","authors":"Shreyas Parthasarathy, Maxime Joos, Lillian B. Hughes, Simon A. Meynell, Taylor A. Morrison, J.D. Risner-Jamtgaard, David M. Weld, Kunal Mukherjee, Ania C. Bleszynski Jayich","doi":"10.1103/physrevapplied.22.024067","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024067","url":null,"abstract":"Many modern-day quantum science experiments rely on high-fidelity measurement of fluorescent signals emitted by the quantum system under study. A pernicious issue encountered when such experiments are conducted near a material interface in vacuum is “laser-induced contamination” (LIC): the gradual accretion of fluorescent contaminants on the surface where a laser is focused. Fluorescence from these contaminants can entirely drown out any signal from, e.g., optically probed color centers in the solid state. Crucially, while LIC appears often in this context, it has not been systematically studied. In this work, we probe the onset and growth rate of LIC for a diamond nitrogen-vacancy center experiment in vacuum, and we correlate the contamination-induced fluorescence intensities to micron-scale physical buildup of contaminant on the diamond surface. Drawing upon similar phenomena previously studied in the space optics community, we use photocatalyzed oxidation of contaminants as a mitigation strategy. We vary the residual oxygen pressure over 9 orders of magnitude and find that LIC growth is inhibited at near-atmospheric oxygen partial pressures, but the growth rate at lower oxygen pressure is nonmonotonic. Finally, we discuss a model for the observed dependence of LIC growth rate on oxygen content and propose methods to extend <i>in situ</i> mitigation of LIC to a wider range of operating pressures.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"60 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-26DOI: 10.1103/physrevapplied.22.024064
Anees Pazhedath, Lorenzo Bastonero, Nicola Marzari, Michele Simoncelli
Alloys based on lanthanum phosphate () are often employed as thermal barrier coatings, due to their low thermal conductivity and structural stability over a wide temperature range. To enhance the thermal-insulation performance of these alloys, it is essential to comprehensively understand the fundamental physics governing their heat conduction. Here, we employ the Wigner formulation of thermal transport in conjunction with first-principles calculations to elucidate how the interplay between anharmonicity and compositional disorder determines the thermal properties of alloys, and discuss the fundamental physics underlying the emergence and coexistence of particlelike and wavelike heat-transport mechanisms. We also show how the Wigner transport equation correctly describes the thermodynamic limit of a compositionally disordered crystal, while the Boltzmann transport equation does not. Our predictions for microscopic vibrational properties (temperature-dependent Raman spectrum) and for macroscopic thermal conductivity are validated against experiments. Finally, we leverage these findings to devise strategies to optimize the performance of thermal barrier coatings.
{"title":"First-principles characterization of thermal conductivity in LaPO4-based alloys","authors":"Anees Pazhedath, Lorenzo Bastonero, Nicola Marzari, Michele Simoncelli","doi":"10.1103/physrevapplied.22.024064","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024064","url":null,"abstract":"Alloys based on lanthanum phosphate (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mrow><mi>La</mi><mi>PO</mi></mrow><mn>4</mn></msub></math>) are often employed as thermal barrier coatings, due to their low thermal conductivity and structural stability over a wide temperature range. To enhance the thermal-insulation performance of these alloys, it is essential to comprehensively understand the fundamental physics governing their heat conduction. Here, we employ the Wigner formulation of thermal transport in conjunction with first-principles calculations to elucidate how the interplay between anharmonicity and compositional disorder determines the thermal properties of <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>La</mi><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><msub><mi>Gd</mi><mi>x</mi></msub><msub><mi>PO</mi><mn>4</mn></msub></math> alloys, and discuss the fundamental physics underlying the emergence and coexistence of particlelike and wavelike heat-transport mechanisms. We also show how the Wigner transport equation correctly describes the thermodynamic limit of a compositionally disordered crystal, while the Boltzmann transport equation does not. Our predictions for microscopic vibrational properties (temperature-dependent Raman spectrum) and for macroscopic thermal conductivity are validated against experiments. Finally, we leverage these findings to devise strategies to optimize the performance of thermal barrier coatings.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"24 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-26DOI: 10.1103/physrevapplied.22.024065
Shuaishuai Yuan, Hong Guo
Electron-phonon (-ph) scattering is a key effect in quantum transport and electronic device physics which is, however, often neglected in atomistic device simulation due to its impractical computational burden. Here we investigate e-ph effects in two-dimensional (2D) FETs, where the injecting source is graphene that inject “Dirac” electrons into the FET channel. Such a Dirac-source FET was experimentally known to have excellent transfer characteristics for its lower off-state current due to the electronic structure of the graphene. By using an approximate but computationally efficient technique (the Zacharias-Giustino method) to capture e-ph scattering, we quantitatively analyze to what extent e-ph scattering affects the operation of Dirac source, as a function of temperature. Our nonequilibrium Green’s function density-functional-theory analysis microscopically reveal the e-ph scattering and we make a comprehensive evaluation of it across real, momentum, and energy spaces, covering both the tunneling and thermionic emission regions. The findings suggest that e-ph scattering does not significantly impact the overall performance of the Dirac-source FETs. For the graphene- device, the e-ph effects amount to somewhat increase the off-state current, which is not significant as to alter the subthreshold property of the transistor. Other factors, such as gate efficiency—determined by the body factor—exhibit a more pronounced influence on device performance for this system.
{"title":"Electron-phonon scattering in two-dimensional Dirac-source transistors","authors":"Shuaishuai Yuan, Hong Guo","doi":"10.1103/physrevapplied.22.024065","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024065","url":null,"abstract":"Electron-phonon (<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>e</mi></math>-ph) scattering is a key effect in quantum transport and electronic device physics which is, however, often neglected in atomistic device simulation due to its impractical computational burden. Here we investigate <i>e</i>-ph effects in two-dimensional (2D) FETs, where the injecting source is graphene that inject “Dirac” electrons into the FET channel. Such a Dirac-source FET was experimentally known to have excellent transfer characteristics for its lower <span>off</span>-state current due to the electronic structure of the graphene. By using an approximate but computationally efficient technique (the Zacharias-Giustino method) to capture <i>e</i>-ph scattering, we quantitatively analyze to what extent <i>e</i>-ph scattering affects the operation of Dirac source, as a function of temperature. Our nonequilibrium Green’s function density-functional-theory analysis microscopically reveal the <i>e</i>-ph scattering and we make a comprehensive evaluation of it across real, momentum, and energy spaces, covering both the tunneling and thermionic emission regions. The findings suggest that <i>e</i>-ph scattering does not significantly impact the overall performance of the Dirac-source FETs. For the graphene-<math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>WSe</mi><mn>2</mn></msub></math> device, the <i>e</i>-ph effects amount to somewhat increase the <span>off</span>-state current, which is not significant as to alter the subthreshold property of the transistor. Other factors, such as gate efficiency—determined by the body factor—exhibit a more pronounced influence on device performance for this system.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"1 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-26DOI: 10.1103/physrevapplied.22.024066
Maik Gaerner, Robin Silber, Tobias Peters, Jaroslav Hamrle, Timo Kuschel
In most studies utilizing the magneto-optic Kerr effect (MOKE), the detected change of polarized light upon reflection from a magnetized sample is supposed to be proportional to the magnetization . However, MOKE signatures quadratic in have also been identified and utilized, e.g., to sense the structural order in Heusler compounds, to detect spin-orbit torque or to image antiferromagnetic domains. In our study, we observe a strong anisotropic MOKE contribution of third order in in (111) thin films, attributed to a cubic magneto-optic tensor . We further show that the angular dependence of cubic MOKE (CMOKE) is affected by the amount of structural domain twinning in the sample. Our detailed study on CMOKE will open up opportunities for CMOKE applications with sensitivity to twinning properties of thin films, e.g., CMOKE spectroscopy and microscopy or time-resolved CMOKE. Furthermore, the in-plane magnetization orientation can be detected with CMOKE when perpendicular incidence light is used, which is suitable for MOKE setups that do not provide oblique incidence.
在大多数利用磁光克尔效应（MOKE）的研究中，从磁化样品反射时检测到的偏振光变化应该与磁化率 M 成正比。然而，与 M 成二次方的 MOKE 信号也已被识别和利用，例如，用于感知 Heusler 化合物中的结构秩序、检测自旋轨道力矩或成像反铁磁域。在我们的研究中，我们观察到镍(111)薄膜中 M 的三阶强各向异性 MOKE 贡献，归因于立方磁光张量∝M3。我们还进一步证明，立方磁致光学（CMOKE）的角度依赖性受到样品中结构域孪晶数量的影响。我们对 CMOKE 的详细研究将为对薄膜孪晶特性敏感的 CMOKE 应用提供机会，例如 CMOKE 光谱和显微镜或时间分辨 CMOKE。此外，当使用垂直入射光时，CMOKE 可检测面内磁化取向，这适用于不提供斜入射光的 MOKE 设置。
{"title":"Cubic magneto-optic Kerr effect in Ni(111) thin films with and without twinning","authors":"Maik Gaerner, Robin Silber, Tobias Peters, Jaroslav Hamrle, Timo Kuschel","doi":"10.1103/physrevapplied.22.024066","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024066","url":null,"abstract":"In most studies utilizing the magneto-optic Kerr effect (MOKE), the detected change of polarized light upon reflection from a magnetized sample is supposed to be proportional to the magnetization <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">M</mi></mrow></math>. However, MOKE signatures quadratic in <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">M</mi></mrow></math> have also been identified and utilized, e.g., to sense the structural order in Heusler compounds, to detect spin-orbit torque or to image antiferromagnetic domains. In our study, we observe a strong anisotropic MOKE contribution of third order in <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"bold\">M</mi></mrow></math> in <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Ni</mi></math>(111) thin films, attributed to a cubic magneto-optic tensor <math display=\"inline\" overflow=\"scroll\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>∝</mo><mspace width=\"0.2em\"></mspace><msup><mrow><mi mathvariant=\"bold\">M</mi></mrow><mn>3</mn></msup></math>. We further show that the angular dependence of cubic MOKE (CMOKE) is affected by the amount of structural domain twinning in the sample. Our detailed study on CMOKE will open up opportunities for CMOKE applications with sensitivity to twinning properties of thin films, e.g., CMOKE spectroscopy and microscopy or time-resolved CMOKE. Furthermore, the in-plane magnetization orientation can be detected with CMOKE when perpendicular incidence light is used, which is suitable for MOKE setups that do not provide oblique incidence.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"52 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-26DOI: 10.1103/physrevapplied.22.024063
Henri Tertilt, Jonas Mensing, Marlon Becker, Wilfred G. van der Wiel, Peter A. Bobbert, Andreas Heuer
Nonlinear behavior in the hopping transport of interacting charges enables reconfigurable logic in disordered dopant network devices, where voltages applied at control electrodes tune the relation between voltages applied at input electrodes and the current measured at an output electrode. From kinetic Monte Carlo simulations we analyze the critical nonlinear aspects of variable-range hopping transport for realizing Boolean logic gates in these devices on three levels. First, we quantify the occurrence of individual gates for random choices of control voltages. We find that linearly inseparable gates such as the xor gate are less likely to occur than linearly separable gates such as the and gate, despite the fact that the number of different regions in the multidimensional control voltage space for which and or xor gates occur is comparable. Second, we use principal-component analysis to characterize the distribution of the output current vectors for the (00,10,01,11) logic input combinations in terms of eigenvectors and eigenvalues of the output covariance matrix. This allows a simple and direct comparison of the behavior of different simulated devices and a comparison to experimental devices. Third, we quantify the nonlinearity in the distribution of the output current vectors necessary for realizing Boolean functionality by introducing three nonlinearity indicators. The analysis provides a physical interpretation of the effects of changing the hopping distance and temperature and is used in a comparison with data generated by a deep neural network trained on a physical device.
{"title":"Critical nonlinear aspects of hopping transport for reconfigurable logic in disordered dopant networks","authors":"Henri Tertilt, Jonas Mensing, Marlon Becker, Wilfred G. van der Wiel, Peter A. Bobbert, Andreas Heuer","doi":"10.1103/physrevapplied.22.024063","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024063","url":null,"abstract":"Nonlinear behavior in the hopping transport of interacting charges enables reconfigurable logic in disordered dopant network devices, where voltages applied at control electrodes tune the relation between voltages applied at input electrodes and the current measured at an output electrode. From kinetic Monte Carlo simulations we analyze the critical nonlinear aspects of variable-range hopping transport for realizing Boolean logic gates in these devices on three levels. First, we quantify the occurrence of individual gates for random choices of control voltages. We find that linearly inseparable gates such as the <span>xor</span> gate are less likely to occur than linearly separable gates such as the <span>and</span> gate, despite the fact that the number of different regions in the multidimensional control voltage space for which <span>and</span> or <span>xor</span> gates occur is comparable. Second, we use principal-component analysis to characterize the distribution of the output current vectors for the (00,10,01,11) logic input combinations in terms of eigenvectors and eigenvalues of the output covariance matrix. This allows a simple and direct comparison of the behavior of different simulated devices and a comparison to experimental devices. Third, we quantify the nonlinearity in the distribution of the output current vectors necessary for realizing Boolean functionality by introducing three nonlinearity indicators. The analysis provides a physical interpretation of the effects of changing the hopping distance and temperature and is used in a comparison with data generated by a deep neural network trained on a physical device.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"23 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1103/physrevapplied.22.024062
John S. Van Dyke, Zackary White, Gregory Quiroz
Zero-noise extrapolation (ZNE), a technique to estimate quantum circuit expectation values through noise scaling and extrapolation, is well studied in the context of quantum computing. We examine the applicability of ZNE to the field of quantum sensing. Focusing on the problem of dc magnetometry using the Ramsey protocol, we show that the sensitivity (in the sense of the minimum detectable signal) does not improve upon using ZNE in the slope detection scheme. On the other hand, signals of sufficiently large magnitude can be estimated more accurately. Our results are robust across various noise models and design choices for the ZNE protocols, including both single-qubit and multiqubit entanglement-based sensing.
{"title":"Mitigating errors in dc magnetometry via zero-noise extrapolation","authors":"John S. Van Dyke, Zackary White, Gregory Quiroz","doi":"10.1103/physrevapplied.22.024062","DOIUrl":"https://doi.org/10.1103/physrevapplied.22.024062","url":null,"abstract":"Zero-noise extrapolation (ZNE), a technique to estimate quantum circuit expectation values through noise scaling and extrapolation, is well studied in the context of quantum computing. We examine the applicability of ZNE to the field of quantum sensing. Focusing on the problem of dc magnetometry using the Ramsey protocol, we show that the sensitivity (in the sense of the minimum detectable signal) does not improve upon using ZNE in the slope detection scheme. On the other hand, signals of sufficiently large magnitude can be estimated more accurately. Our results are robust across various noise models and design choices for the ZNE protocols, including both single-qubit and multiqubit entanglement-based sensing.","PeriodicalId":20109,"journal":{"name":"Physical Review Applied","volume":"67 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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