Xing-Yu Yang, Jia-Ying Cao, Xiao-hang Ma, Shi-Hao Ren, Yong-Li Liu, F. S. Meng, Yang Qi
Due to the differences in the treatment methods of the electron–ion interaction and the critical strain mode of the transition from semimetals to semiconductors, the corresponding strain modulation mechanism in layered bismuth (Bi) crystals remains elusive. In this work, the effects of van der Waals (vdW) correction on the crystal structure and electrical properties of Bi in an equilibrium/strained state are comparatively studied based on the density functional theory. It is found that vdW corrections can better describe the layered crystal and bandgap structure of Bi under equilibrium/strain conditions. With the vdW modification, bismuth can be converted from a semimetal to a semiconductor within a small compression range that is experimentally available. This transition is induced by the transfer of the conduction band minimum and the valence band maximum and is related to the competition of the near-band edge energy state near the Fermi level of bismuth. The present results not only provide guidance for the accurate study of the crystal structure and electronic properties of complex model systems, such as Bi or Bi-based inherently nanostructured materials, but also reveal strain regulation mechanism of Bi and predict its potential application in the semiconductor electronic devices.
{"title":"Effect of bonding description and strain regulation on the conductive transition of Bi semimetal","authors":"Xing-Yu Yang, Jia-Ying Cao, Xiao-hang Ma, Shi-Hao Ren, Yong-Li Liu, F. S. Meng, Yang Qi","doi":"10.1063/5.0206964","DOIUrl":"https://doi.org/10.1063/5.0206964","url":null,"abstract":"Due to the differences in the treatment methods of the electron–ion interaction and the critical strain mode of the transition from semimetals to semiconductors, the corresponding strain modulation mechanism in layered bismuth (Bi) crystals remains elusive. In this work, the effects of van der Waals (vdW) correction on the crystal structure and electrical properties of Bi in an equilibrium/strained state are comparatively studied based on the density functional theory. It is found that vdW corrections can better describe the layered crystal and bandgap structure of Bi under equilibrium/strain conditions. With the vdW modification, bismuth can be converted from a semimetal to a semiconductor within a small compression range that is experimentally available. This transition is induced by the transfer of the conduction band minimum and the valence band maximum and is related to the competition of the near-band edge energy state near the Fermi level of bismuth. The present results not only provide guidance for the accurate study of the crystal structure and electronic properties of complex model systems, such as Bi or Bi-based inherently nanostructured materials, but also reveal strain regulation mechanism of Bi and predict its potential application in the semiconductor electronic devices.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"32 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Md. Bakey Billa, Mohammad Tariqul Islam, Touhidul Alam, Md. Shabiul Islam, Asraf Mohamed Moubark, Haitham Alsaif, Saleh Albadran, Ahmed Alzamil, Ahmed S. Alshammari
This paper presents a conductive component tailored to a flexible substrate using Al-doped CoxCa(0.90−x)Ni0.10Fe2O4 (x = 0.25, 0.50, and 0.75) for visible to near-infrared (NIR) spectra in magneto-optical applications. The developed nanoparticles show uniformity, nanosized grains, and capillary nanopore fusion characteristics, which are confirmed by x-ray diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy analyses, respectively. The XRD analysis revealed crystallite sizes of 33.36, 37.08, and 44.25 nm and particle sizes of 45.6, 34.6, and 31.5 nm for the compositions x = 0.25, 0.50, and 0.75, respectively. The Al-doped nanoparticles are converted to a flexible solid substrate utilizing a polyvinyl alcohol matrix, facilitating conformality to build complex shapes and broadening their application scope. The structure shows higher absorption across 450–720 nm, 480–720 nm, and 200–850 nm spectra for x = 0.25, 0.50, and 0.75, respectively. The distinctive magnetic and electrical properties are also evaluated through magnetic force microscopy and conductive atomic force microscopy, culminating in a substrate with exceptional control over light–matter interactions with smooth surfaces with lower surface roughness. The vibrating sample magnetometer analysis of the substrate shows how varying cobalt content affects magnetic properties relevant for visible to near-infrared (NIR) applications, offering insights into coercivity, magnetization, and retentivity changes at different x values. The perceptible novelties of this work are advancements in material sciences aimed at enhancing light manipulation and flexibility for electronic devices.
本文介绍了使用掺铝 CoxCa(0.90-x)Ni0.10Fe2O4（x = 0.25、0.50 和 0.75）为柔性基底定制的导电元件，可用于磁光应用中的可见光至近红外（NIR）光谱。X 射线衍射（XRD）、场发射扫描电子显微镜和能量色散 X 射线光谱分析分别证实了所开发的纳米粒子具有均匀性、纳米粒度和毛细管纳米孔融合特性。X 射线衍射分析表明，成分 x = 0.25、0.50 和 0.75 时，结晶尺寸分别为 33.36、37.08 和 44.25 纳米，颗粒尺寸分别为 45.6、34.6 和 31.5 纳米。利用聚乙烯醇基质将掺铝纳米粒子转化为柔性固体基底，有利于构建复杂的形状并扩大其应用范围。当 x = 0.25、0.50 和 0.75 时，该结构分别在 450-720 纳米、480-720 纳米和 200-850 纳米光谱范围内显示出更高的吸收率。此外，还通过磁力显微镜和导电原子力显微镜对独特的磁性和电性进行了评估，最终得到了一种对光与物质的相互作用具有卓越控制能力的基底，其表面光滑，粗糙度较低。对基板进行的振动样品磁力计分析表明，不同的钴含量如何影响与可见光到近红外（NIR）应用相关的磁性能，从而深入了解不同 x 值下的矫顽力、磁化率和保持率变化。这项工作的新颖之处在于推动了材料科学的发展，旨在增强电子设备的光操控性和灵活性。
{"title":"Structural, morphological, optical, electrical, and magnetic properties of aluminum-doped CoxCa(0.90−x)Ni0.10Fe2O4 flexible substrate for visible to NIR spectra applications","authors":"Md. Bakey Billa, Mohammad Tariqul Islam, Touhidul Alam, Md. Shabiul Islam, Asraf Mohamed Moubark, Haitham Alsaif, Saleh Albadran, Ahmed Alzamil, Ahmed S. Alshammari","doi":"10.1063/5.0203785","DOIUrl":"https://doi.org/10.1063/5.0203785","url":null,"abstract":"This paper presents a conductive component tailored to a flexible substrate using Al-doped CoxCa(0.90−x)Ni0.10Fe2O4 (x = 0.25, 0.50, and 0.75) for visible to near-infrared (NIR) spectra in magneto-optical applications. The developed nanoparticles show uniformity, nanosized grains, and capillary nanopore fusion characteristics, which are confirmed by x-ray diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy analyses, respectively. The XRD analysis revealed crystallite sizes of 33.36, 37.08, and 44.25 nm and particle sizes of 45.6, 34.6, and 31.5 nm for the compositions x = 0.25, 0.50, and 0.75, respectively. The Al-doped nanoparticles are converted to a flexible solid substrate utilizing a polyvinyl alcohol matrix, facilitating conformality to build complex shapes and broadening their application scope. The structure shows higher absorption across 450–720 nm, 480–720 nm, and 200–850 nm spectra for x = 0.25, 0.50, and 0.75, respectively. The distinctive magnetic and electrical properties are also evaluated through magnetic force microscopy and conductive atomic force microscopy, culminating in a substrate with exceptional control over light–matter interactions with smooth surfaces with lower surface roughness. The vibrating sample magnetometer analysis of the substrate shows how varying cobalt content affects magnetic properties relevant for visible to near-infrared (NIR) applications, offering insights into coercivity, magnetization, and retentivity changes at different x values. The perceptible novelties of this work are advancements in material sciences aimed at enhancing light manipulation and flexibility for electronic devices.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"6 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Strain sensors based on porous conductive polymers (CPCs) have garnered growing research interest for their potential applications in motion detection, healthcare, human–computer interaction, and artificial intelligence. However, the complexity of CPC processing makes it difficult to achieve the controlled design of microscopic porous structures, leading to simple and random porous structures, thus limiting their further use in the field of pressure sensing. This paper presents a strain sensor with a high-performance, wood-like structure composed of flexible conductive carbon black/plastic polyurethane foam (BWCT) using a bidirectional freeze casting process. The results show that, compared with conventional random freezing and unidirectional freezing, the bidirectional freeze casting process can effectively realize multiscale control of the composite structure, which results in a good laminar porous structure of the prepared BWCT. This parallel laminar structure not only contributes to the layered transfer of stresses but also avoids the local concentration of stresses. At the same time, it significantly increases the directional electrical conduction ability, which results in high sensing stability performance. In particular, the BWCT sensors had a wide detection range (80%), a lower limit of detection (0.2%), rapid response and relaxation times (200 ms), as well as exceptional durability (>2000 cycles). Furthermore, the BWCT was integrated into a wearable sensor to monitor various human motions, including arm bending, squatting, and walking, demonstrating reliable detection performance. Altogether, the BWCT sensors are promising in expanding the application but also offer guidance for designing high-performance wearable strain sensors.
{"title":"Nature-inspired wood-like TPU/CB aerogels for high performance flexible strain sensors","authors":"Guanyu Wang, Yadong Yang, Wenzhe Cao, Caichao Wan","doi":"10.1063/5.0205597","DOIUrl":"https://doi.org/10.1063/5.0205597","url":null,"abstract":"Strain sensors based on porous conductive polymers (CPCs) have garnered growing research interest for their potential applications in motion detection, healthcare, human–computer interaction, and artificial intelligence. However, the complexity of CPC processing makes it difficult to achieve the controlled design of microscopic porous structures, leading to simple and random porous structures, thus limiting their further use in the field of pressure sensing. This paper presents a strain sensor with a high-performance, wood-like structure composed of flexible conductive carbon black/plastic polyurethane foam (BWCT) using a bidirectional freeze casting process. The results show that, compared with conventional random freezing and unidirectional freezing, the bidirectional freeze casting process can effectively realize multiscale control of the composite structure, which results in a good laminar porous structure of the prepared BWCT. This parallel laminar structure not only contributes to the layered transfer of stresses but also avoids the local concentration of stresses. At the same time, it significantly increases the directional electrical conduction ability, which results in high sensing stability performance. In particular, the BWCT sensors had a wide detection range (80%), a lower limit of detection (0.2%), rapid response and relaxation times (200 ms), as well as exceptional durability (>2000 cycles). Furthermore, the BWCT was integrated into a wearable sensor to monitor various human motions, including arm bending, squatting, and walking, demonstrating reliable detection performance. Altogether, the BWCT sensors are promising in expanding the application but also offer guidance for designing high-performance wearable strain sensors.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"9 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Krishnia, B. Bony, E. Rongione, L. Moreno Vicente-Arche, T. Denneulin, A. Pezo, Y. Lu, R. E. Dunin-Borkowski, S. Collin, A. Fert, J.-M. George, N. Reyren, V. Cros, H. Jaffrès
The generation of large spin currents, and the associated spin torques, which are at the heart of modern spintronics, has long been achieved by charge-to-spin conversion mechanisms, i.e., the spin Hall effect and/or the Rashba–Edelstein effect, intrinsically linked to strong spin–orbit coupling. Recently, a novel path has been predicted and observed for achieving significant current-induced torques originating from light elements, hence possessing weak spin–orbit interaction. These findings point out to the potential involvement of the orbital counterpart of electrons, namely the orbital Hall and orbital Rashba–Edelstein effects. In this study, we aim at quantifying these orbital-related contributions to the effective torques acting on a thin Co layer in different systems. First, we demonstrate in Pt|Co|Cu|AlOx stacking a comparable torque strength coming from the conversion due to the orbital Rashba–Edelstein effect at the Cu|AlOx interface and the one from the effective spin Hall effect in the bottom Pt|Co system. Second, in order to amplify the orbital-to-spin conversion, we investigate the impact of an intermediate Pt layer in Co|Pt|Cu|CuOx. From the Pt thickness dependence of the effective torques determined by harmonic Hall measurements complemented by spin Hall magneto-resistance and THz spectroscopy experiments, we demonstrate that a large orbital Rashba–Edelstein effect is present at the Cu|CuOx interface, leading to a twofold enhancement of the net torques on Co for the optimal Pt thickness. Our findings not only demonstrate the crucial role that orbital currents can play in low-dimensional systems with weak spin–orbit coupling but also reveal that they enable more energy efficient manipulation of magnetization in spintronic devices.
作为现代自旋电子学核心的大自旋电流和相关自旋转矩的产生，长期以来一直是通过电荷-自旋转换机制（即自旋霍尔效应和/或拉什巴-爱德斯坦效应）实现的，这与强自旋轨道耦合有着内在联系。最近，人们预测并观察到了一种新的途径，即通过轻元素（因此具有弱自旋轨道相互作用）实现显著的电流诱导转矩。这些发现指出了电子轨道对应物的潜在参与，即轨道霍尔效应和轨道拉什巴-爱德斯坦效应。在本研究中，我们旨在量化这些轨道效应对不同体系中作用于 Co 薄层的有效转矩的贡献。首先，我们证明了在 Pt|Co|Cu|AlOx 堆叠中，Cu|AlOx 界面的轨道 Rashba-Edelstein 效应和底部 Pt|Co 系统的有效自旋霍尔效应所产生的转换扭矩强度相当。其次，为了放大轨道到自旋的转换，我们研究了 Co|Pt|Cu|CuOx 中中间铂层的影响。通过谐波霍尔测量以及自旋霍尔磁阻和太赫兹光谱实验确定的有效转矩的铂厚度依赖性，我们证明了在 Cu|CuOx 界面存在着巨大的轨道拉什巴-爱德斯坦效应，从而导致在最佳铂厚度下 Co 上的净转矩增强了两倍。我们的发现不仅证明了轨道电流在自旋轨道耦合较弱的低维系统中可以发挥关键作用，而且揭示了轨道电流可以在自旋电子器件中实现更高效的磁化操纵。
{"title":"Quantifying the large contribution from orbital Rashba–Edelstein effect to the effective damping-like torque on magnetization","authors":"S. Krishnia, B. Bony, E. Rongione, L. Moreno Vicente-Arche, T. Denneulin, A. Pezo, Y. Lu, R. E. Dunin-Borkowski, S. Collin, A. Fert, J.-M. George, N. Reyren, V. Cros, H. Jaffrès","doi":"10.1063/5.0198970","DOIUrl":"https://doi.org/10.1063/5.0198970","url":null,"abstract":"The generation of large spin currents, and the associated spin torques, which are at the heart of modern spintronics, has long been achieved by charge-to-spin conversion mechanisms, i.e., the spin Hall effect and/or the Rashba–Edelstein effect, intrinsically linked to strong spin–orbit coupling. Recently, a novel path has been predicted and observed for achieving significant current-induced torques originating from light elements, hence possessing weak spin–orbit interaction. These findings point out to the potential involvement of the orbital counterpart of electrons, namely the orbital Hall and orbital Rashba–Edelstein effects. In this study, we aim at quantifying these orbital-related contributions to the effective torques acting on a thin Co layer in different systems. First, we demonstrate in Pt|Co|Cu|AlOx stacking a comparable torque strength coming from the conversion due to the orbital Rashba–Edelstein effect at the Cu|AlOx interface and the one from the effective spin Hall effect in the bottom Pt|Co system. Second, in order to amplify the orbital-to-spin conversion, we investigate the impact of an intermediate Pt layer in Co|Pt|Cu|CuOx. From the Pt thickness dependence of the effective torques determined by harmonic Hall measurements complemented by spin Hall magneto-resistance and THz spectroscopy experiments, we demonstrate that a large orbital Rashba–Edelstein effect is present at the Cu|CuOx interface, leading to a twofold enhancement of the net torques on Co for the optimal Pt thickness. Our findings not only demonstrate the crucial role that orbital currents can play in low-dimensional systems with weak spin–orbit coupling but also reveal that they enable more energy efficient manipulation of magnetization in spintronic devices.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"16 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Olivio Chiatti, Johannes Boy, Christian Heyn, Wolfgang Hansen, Saskia F. Fischer
The crossover from quasi-two- to quasi-one-dimensional electron transport subject to transverse electric fields and perpendicular magnetic fields is studied in the diffusive to quasi-ballistic and zero-field to quantum Hall regime. In-plane gates and Hall-bars have been fabricated from an InGaAs/InAlAs/InAs quantum well hosting a 2DEG with a carrier density of about 6.8 × 1011 cm−2, a mobility of 1.8 × 105 cm2/Vs, and an effective mass of 0.042me after illumination. Magnetotransport measurements at temperatures down to 50 mK and fields up to 12 T yield a high effective Landé factor of g*=16, enabling the resolution of spin-split subbands at magnetic fields of 2.5 T. In the quantum Hall regime, electrostatic control of an effective constriction width enables steering of the reflection and transmission of edge channels, allowing a separation of fully spin-polarized edge channels at filling factors ν = 1 und ν = 2. A change in the orientation of a transverse in-plane electric field in the constriction shifts the transition between Zeeman-split quantum Hall plateaus by ΔB ≈ 0.1 T and is consistent with an effective magnetic field of Beff ≈ 0.13 T by spin-dependent backscattering, indicating a change in the spin-split density of states.
{"title":"In-plane gate induced transition asymmetry of spin-resolved Landau levels in InAs-based quantum wells","authors":"Olivio Chiatti, Johannes Boy, Christian Heyn, Wolfgang Hansen, Saskia F. Fischer","doi":"10.1063/5.0203097","DOIUrl":"https://doi.org/10.1063/5.0203097","url":null,"abstract":"The crossover from quasi-two- to quasi-one-dimensional electron transport subject to transverse electric fields and perpendicular magnetic fields is studied in the diffusive to quasi-ballistic and zero-field to quantum Hall regime. In-plane gates and Hall-bars have been fabricated from an InGaAs/InAlAs/InAs quantum well hosting a 2DEG with a carrier density of about 6.8 × 1011 cm−2, a mobility of 1.8 × 105 cm2/Vs, and an effective mass of 0.042me after illumination. Magnetotransport measurements at temperatures down to 50 mK and fields up to 12 T yield a high effective Landé factor of g*=16, enabling the resolution of spin-split subbands at magnetic fields of 2.5 T. In the quantum Hall regime, electrostatic control of an effective constriction width enables steering of the reflection and transmission of edge channels, allowing a separation of fully spin-polarized edge channels at filling factors ν = 1 und ν = 2. A change in the orientation of a transverse in-plane electric field in the constriction shifts the transition between Zeeman-split quantum Hall plateaus by ΔB ≈ 0.1 T and is consistent with an effective magnetic field of Beff ≈ 0.13 T by spin-dependent backscattering, indicating a change in the spin-split density of states.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"42 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isabel Streicher, Patrik Straňák, Lutz Kirste, Mario Prescher, Stefan Müller, Stefano Leone
Wurtzite AlN alloyed with group 3 elements Sc and Y boosts the performance of GaN-based high-electron-mobility transistors (HEMTs) significantly as they increase the spontaneous polarization of the barrier layer and, thus, enhance the charge carrier density ns in the two-dimensional electron gas (2DEG) formed at the interface with the GaN channel. The emerging nitride Al1−xYxN additionally features an a lattice parameter matching to that of GaN at x = 0.07–0.11, allowing for the growth of strain-free barriers. Here, we demonstrate the growth of Al1−xYxN/GaN heterostructures for HEMTs by metal–organic chemical vapor deposition for the first time. The effect of the Y concentrations on the 2DEG is investigated in a Y concentration range from 3% to 15%. At 8% Y, a record mobility of 3200 cm2/(Vs) was measured at a low temperature (7 K). Room and low-temperature ns was at 1–2 × 1013 cm−2. Al0.92Y0.08N barriers were coherently strained to the GaN channel for barrier thicknesses from 5 to 15 nm. Finally, the deposition of Al1−xYxN/GaN heterostructures deposited on 4″ 4H–SiC wafers had a room-temperature mobility close to 1400 cm2/(Vs). AlYN/GaN heterostructures may offer advantages over AlScN/GaN heterostructures not only for the lower price and higher abundance of the raw material but also in terms of electrical characteristics and may be more suitable for power amplifying applications due to increased electron mobility.
{"title":"Two-dimensional electron gases in AlYN/GaN heterostructures grown by metal–organic chemical vapor deposition","authors":"Isabel Streicher, Patrik Straňák, Lutz Kirste, Mario Prescher, Stefan Müller, Stefano Leone","doi":"10.1063/5.0203156","DOIUrl":"https://doi.org/10.1063/5.0203156","url":null,"abstract":"Wurtzite AlN alloyed with group 3 elements Sc and Y boosts the performance of GaN-based high-electron-mobility transistors (HEMTs) significantly as they increase the spontaneous polarization of the barrier layer and, thus, enhance the charge carrier density ns in the two-dimensional electron gas (2DEG) formed at the interface with the GaN channel. The emerging nitride Al1−xYxN additionally features an a lattice parameter matching to that of GaN at x = 0.07–0.11, allowing for the growth of strain-free barriers. Here, we demonstrate the growth of Al1−xYxN/GaN heterostructures for HEMTs by metal–organic chemical vapor deposition for the first time. The effect of the Y concentrations on the 2DEG is investigated in a Y concentration range from 3% to 15%. At 8% Y, a record mobility of 3200 cm2/(Vs) was measured at a low temperature (7 K). Room and low-temperature ns was at 1–2 × 1013 cm−2. Al0.92Y0.08N barriers were coherently strained to the GaN channel for barrier thicknesses from 5 to 15 nm. Finally, the deposition of Al1−xYxN/GaN heterostructures deposited on 4″ 4H–SiC wafers had a room-temperature mobility close to 1400 cm2/(Vs). AlYN/GaN heterostructures may offer advantages over AlScN/GaN heterostructures not only for the lower price and higher abundance of the raw material but also in terms of electrical characteristics and may be more suitable for power amplifying applications due to increased electron mobility.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"24 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oxide ionotronics is an interdisciplinary field in which systems and devices rely on the migration of ions/ionic defects to alter or drive functionality. In this perspective, we focus on epitaxial oxide heterostructures and the contributing roles of oxygen vacancies and interfaces in ionotronics. We begin with a description of oxygen vacancy behavior, with a focus on vacancy ordering and the effects of interfaces and electric fields on particular epitaxial oxide systems. We then emphasize the use of synchrotron x-ray techniques for investigating system structure and dynamics in situ at interfaces and surfaces. Finally, an outlook on the future of epitaxial oxide ionotronics is provided, and several key areas for research are identified, such as freestanding heterostructures, combinatorial synthesis and machine learning, and next-generation synchrotron x-ray characterization.
氧化物离子电子学是一个跨学科领域，其中的系统和器件依靠离子/离子缺陷的迁移来改变或驱动功能。在这一视角中，我们重点关注外延氧化物异质结构以及氧空位和界面在离子电子学中的作用。我们首先描述了氧空位行为，重点是空位排序以及界面和电场对特定外延氧化物系统的影响。然后，我们强调使用同步辐射 X 射线技术在界面和表面现场研究系统结构和动力学。最后，我们展望了外延氧化物离子电子学的未来，并确定了几个关键的研究领域，如独立异质结构、组合合成和机器学习，以及下一代同步辐射 X 射线表征。
{"title":"Epitaxial oxide ionotronics: Interfaces and oxygen vacancies","authors":"Jill K. Wenderott, Tadesse Billo, Dillon D. Fong","doi":"10.1063/5.0206822","DOIUrl":"https://doi.org/10.1063/5.0206822","url":null,"abstract":"Oxide ionotronics is an interdisciplinary field in which systems and devices rely on the migration of ions/ionic defects to alter or drive functionality. In this perspective, we focus on epitaxial oxide heterostructures and the contributing roles of oxygen vacancies and interfaces in ionotronics. We begin with a description of oxygen vacancy behavior, with a focus on vacancy ordering and the effects of interfaces and electric fields on particular epitaxial oxide systems. We then emphasize the use of synchrotron x-ray techniques for investigating system structure and dynamics in situ at interfaces and surfaces. Finally, an outlook on the future of epitaxial oxide ionotronics is provided, and several key areas for research are identified, such as freestanding heterostructures, combinatorial synthesis and machine learning, and next-generation synchrotron x-ray characterization.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"47 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140832860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The magneto-optical Kerr effect (MOKE) in monodomain bismuth ferrite (BiFeO3) thin films was investigated under applied electric fields and light irradiation. The field-swept MOKE measurements show that the Kerr rotation of BiFeO3 changes under applied electric fields or light irradiation. The piezoresponse force microscopy measurements found that the variation in electrical polarization at the BiFeO3 surface was similar under an applied electric field and ultraviolet irradiation, confirming that the Kerr rotation of BiFeO3 can be controlled using both electric fields and light irradiation. This paper presents a method to couple a magnetic field with an electric field or light irradiation via the Kerr angle measurements of BiFeO3, providing a concept for fabricating multifunctional devices in oxide electronics.
{"title":"Measurement of the coupling of magnetism with electricity or light irradiation in BiFeO3 using the Kerr angle","authors":"Siwat Polin, Peerawat Laohana, Jirapat Kullapapinyokol, Warakorn Jindata, Supansa Musikajaroen, Aissara Rasritat, Hideki Nakajima, Wittawat Saenrang, Santi Maensiri, Chang-Beom Eom, Worawat Meevasana","doi":"10.1063/5.0194274","DOIUrl":"https://doi.org/10.1063/5.0194274","url":null,"abstract":"The magneto-optical Kerr effect (MOKE) in monodomain bismuth ferrite (BiFeO3) thin films was investigated under applied electric fields and light irradiation. The field-swept MOKE measurements show that the Kerr rotation of BiFeO3 changes under applied electric fields or light irradiation. The piezoresponse force microscopy measurements found that the variation in electrical polarization at the BiFeO3 surface was similar under an applied electric field and ultraviolet irradiation, confirming that the Kerr rotation of BiFeO3 can be controlled using both electric fields and light irradiation. This paper presents a method to couple a magnetic field with an electric field or light irradiation via the Kerr angle measurements of BiFeO3, providing a concept for fabricating multifunctional devices in oxide electronics.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"95 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140833084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dianxiang Ji, Yi Zhang, Wei Mao, Min Gu, Yiping Xiao, Yang Yang, Wei Guo, Zhengbin Gu, Jian Zhou, Peng Wang, Yuefeng Nie, Xiaoqing Pan
Atomic-level control of complex oxide heterostructure interfaces has resulted in unprecedented properties and functionalities. The majority of oxide heterointerfaces being intensively investigated maintain lattice coherence and exhibit a flawless epitaxial alignment between the films and the substrates. Here, we report the engineering of a charged incoherent BiFeO3/SrTiO3 interface using a tailored deposition sequence in reactive oxide molecular beam epitaxy. By introducing an additional iron oxide layer to disrupt the lattice coherence at the interface, the overlying BiFeO3 is stabilized in a tetragonal phase with its enhanced ferroelectric polarization pointing toward the SrTiO3 substrate, which drives free electrons to accumulate at the incoherent interface. Our findings reveal how controlling lattice coherence at oxide heterointerfaces can open new avenues for fabricating artificial oxide heterostructures with unique properties through precise interface engineering.
{"title":"Engineering of a charged incoherent BiFeO3/SrTiO3 interface","authors":"Dianxiang Ji, Yi Zhang, Wei Mao, Min Gu, Yiping Xiao, Yang Yang, Wei Guo, Zhengbin Gu, Jian Zhou, Peng Wang, Yuefeng Nie, Xiaoqing Pan","doi":"10.1063/5.0203518","DOIUrl":"https://doi.org/10.1063/5.0203518","url":null,"abstract":"Atomic-level control of complex oxide heterostructure interfaces has resulted in unprecedented properties and functionalities. The majority of oxide heterointerfaces being intensively investigated maintain lattice coherence and exhibit a flawless epitaxial alignment between the films and the substrates. Here, we report the engineering of a charged incoherent BiFeO3/SrTiO3 interface using a tailored deposition sequence in reactive oxide molecular beam epitaxy. By introducing an additional iron oxide layer to disrupt the lattice coherence at the interface, the overlying BiFeO3 is stabilized in a tetragonal phase with its enhanced ferroelectric polarization pointing toward the SrTiO3 substrate, which drives free electrons to accumulate at the incoherent interface. Our findings reveal how controlling lattice coherence at oxide heterointerfaces can open new avenues for fabricating artificial oxide heterostructures with unique properties through precise interface engineering.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"30 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140833142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shuyu Cheng, Binzhi Liu, Igor Lyalin, Wenyi Zhou, Jinwoo Hwang, Roland K. Kawakami
Kagome lattices have garnered substantial interest because their band structure consists of topological flat bands and Dirac cones. The RMn6Sn6 (R = rare earth) compounds are particularly interesting because of the existence of the large intrinsic anomalous Hall effect (AHE), which originates from the gapped Dirac cones near the Fermi level. This makes RMn6Sn6 an outstanding candidate for realizing the high-temperature quantum AHE. The growth of RMn6Sn6 thin films is beneficial for both fundamental research and potential applications. However, most of the studies on RMn6Sn6 have focused on bulk crystals, and the synthesis of RMn6Sn6 thin films has not been reported so far. Here, we report the atomic layer molecular beam epitaxy growth, structural and magnetic characterizations, and transport properties of ErMn6Sn6 and TbMn6Sn6 thin films. It is especially noteworthy that TbMn6Sn6 thin films have out-of-plane magnetic anisotropy, which is important for realizing the quantum AHE. Our work paves the avenue toward the control of the AHE using devices patterned from RMn6Sn6 thin films.
{"title":"Atomic layer molecular beam epitaxy of kagome magnet RMn6Sn6 (R = Er, Tb) thin films","authors":"Shuyu Cheng, Binzhi Liu, Igor Lyalin, Wenyi Zhou, Jinwoo Hwang, Roland K. Kawakami","doi":"10.1063/5.0182595","DOIUrl":"https://doi.org/10.1063/5.0182595","url":null,"abstract":"Kagome lattices have garnered substantial interest because their band structure consists of topological flat bands and Dirac cones. The RMn6Sn6 (R = rare earth) compounds are particularly interesting because of the existence of the large intrinsic anomalous Hall effect (AHE), which originates from the gapped Dirac cones near the Fermi level. This makes RMn6Sn6 an outstanding candidate for realizing the high-temperature quantum AHE. The growth of RMn6Sn6 thin films is beneficial for both fundamental research and potential applications. However, most of the studies on RMn6Sn6 have focused on bulk crystals, and the synthesis of RMn6Sn6 thin films has not been reported so far. Here, we report the atomic layer molecular beam epitaxy growth, structural and magnetic characterizations, and transport properties of ErMn6Sn6 and TbMn6Sn6 thin films. It is especially noteworthy that TbMn6Sn6 thin films have out-of-plane magnetic anisotropy, which is important for realizing the quantum AHE. Our work paves the avenue toward the control of the AHE using devices patterned from RMn6Sn6 thin films.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"155 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140805617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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