Masayuki Iio, Tomohiro Yokoyama, Takeshi Inaoka, H. Ishihara
Plasmon is a collective excitation in metals formed through the Coulomb interaction between individual excitations of electron-hole pairs. In many previous studies on the plasmonic response, the role of the longitudinal field has been focused almost exclusively on the light-induced plasmonic phenomena, e.g., hot-carrier generation. In our previous study [Phys. Rev. B 105, 165408 (2022)], we have revealed the significant contribution of the transverse electromagnetic field to connect plasmons and electron-hole pairs in nanostructures based on the self-consistent and nonlocal response theory. In this study, we examine how this contribution appears depending on the system parameters, e.g., length and refractive index. The elucidation of roles of coherent coupling between the collective and individual excitations by the transverse field will lead to the principle of controlling bidirectional energy transfer between the plasmons and electron-hole pairs, which could significantly enhance hot-carrier generation efficiency.
等离子体是金属中的一种集体激发，通过电子-空穴对的单个激发之间的库仑相互作用而形成。在以往许多关于等离子响应的研究中，纵向场的作用几乎都集中在光诱导的等离子现象上，例如热载流子的产生。在我们之前的研究[Phys. Rev. B 105, 165408 (2022)]中，我们基于自洽和非局部响应理论揭示了横向电磁场对连接纳米结构中的质子和电子-空穴对的重要贡献。在本研究中，我们研究了横向电磁场的贡献如何取决于系统参数，如长度和折射率。通过阐明横向场在集体激发和个体激发之间的相干耦合作用，我们将找到控制质子和电子-电洞对之间双向能量转移的原理，从而显著提高热载流子的生成效率。
{"title":"Nanorod Size Dependence of Coherent Coupling between Individual and Collective Excitations via Transverse Electromagnetic Field","authors":"Masayuki Iio, Tomohiro Yokoyama, Takeshi Inaoka, H. Ishihara","doi":"10.7566/jpsj.93.024701","DOIUrl":"https://doi.org/10.7566/jpsj.93.024701","url":null,"abstract":"Plasmon is a collective excitation in metals formed through the Coulomb interaction between individual excitations of electron-hole pairs. In many previous studies on the plasmonic response, the role of the longitudinal field has been focused almost exclusively on the light-induced plasmonic phenomena, e.g., hot-carrier generation. In our previous study [Phys. Rev. B 105, 165408 (2022)], we have revealed the significant contribution of the transverse electromagnetic field to connect plasmons and electron-hole pairs in nanostructures based on the self-consistent and nonlocal response theory. In this study, we examine how this contribution appears depending on the system parameters, e.g., length and refractive index. The elucidation of roles of coherent coupling between the collective and individual excitations by the transverse field will lead to the principle of controlling bidirectional energy transfer between the plasmons and electron-hole pairs, which could significantly enhance hot-carrier generation efficiency.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139282592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The tunnel current (TC) and valley current (VC) are crucial in realizing high-speed and energy-saving in next-generation devices. This paper presents the TC and VC link in the partially overlapped graphene. Under the vertical electric field, the two graphene layers have the opposite AB sublattice symmetry, followed by a block on the intravalley transmission. In the allowed intervalley transmission, the difference in the phase of the decay factor prefers only one of the valleys in the output according to the overlapped length. These results suggest that the band gap with no edge state is a new platform of valleytronics.
隧道电流（TC）和山谷电流（VC）对于实现下一代器件的高速和节能至关重要。本文介绍了部分重叠石墨烯中的隧道电流和谷电流链路。在垂直电场作用下，两层石墨烯具有相反的 AB 亚晶格对称性，从而阻碍了谷内传输。在允许的谷间传输中，衰减因子的相位差根据重叠长度只偏好输出中的一个谷。这些结果表明，无边缘状态的带隙是谷电技术的一个新平台。
{"title":"Tunnel Valley Current Filter in the Partially Overlapped Graphene under the Vertical Electric Field","authors":"Ryo Tamura","doi":"10.7566/jpsj.92.123704","DOIUrl":"https://doi.org/10.7566/jpsj.92.123704","url":null,"abstract":"The tunnel current (TC) and valley current (VC) are crucial in realizing high-speed and energy-saving in next-generation devices. This paper presents the TC and VC link in the partially overlapped graphene. Under the vertical electric field, the two graphene layers have the opposite AB sublattice symmetry, followed by a block on the intravalley transmission. In the allowed intervalley transmission, the difference in the phase of the decay factor prefers only one of the valleys in the output according to the overlapped length. These results suggest that the band gap with no edge state is a new platform of valleytronics.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139307918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A ferroaxial ordering, which appears without mirror symmetry parallel to an electric axial moment, is described by a ferroic alignment of the electric toroidal (ET) dipole rather than the conventional electric and magnetic dipoles. Although its emergence requires neither spatial inversion nor time-reversal symmetry breakings, unconventional transverse responses between the conjugate physical quantities have been proposed, which are qualitatively different from those in multiferroic systems without both spatial inversion and time-reversal symmetries. We theoretically investigate a general relationship between ferroaxial ordering and its characteristic response tensor. We show that various rotational responses corresponding to an antisymmetric tensor component are related to the ferroaxial ordering based on symmetry analysis. Among them, we propose that second-order nonlinear magnetostriction, where the strain is induced by a second-order magnetic field, is one of the experimental setups to identify the ferroaxial ordering. We show its temperature and magnetic-field-angle dependence by analyzing a fundamental $d$-orbital model under the tetragonal symmetry.
{"title":"Rotational Response Induced by Electric Toroidal Dipole","authors":"Akimitsu Kirikoshi, S. Hayami","doi":"10.7566/JPSJ.92.123703","DOIUrl":"https://doi.org/10.7566/JPSJ.92.123703","url":null,"abstract":"A ferroaxial ordering, which appears without mirror symmetry parallel to an electric axial moment, is described by a ferroic alignment of the electric toroidal (ET) dipole rather than the conventional electric and magnetic dipoles. Although its emergence requires neither spatial inversion nor time-reversal symmetry breakings, unconventional transverse responses between the conjugate physical quantities have been proposed, which are qualitatively different from those in multiferroic systems without both spatial inversion and time-reversal symmetries. We theoretically investigate a general relationship between ferroaxial ordering and its characteristic response tensor. We show that various rotational responses corresponding to an antisymmetric tensor component are related to the ferroaxial ordering based on symmetry analysis. Among them, we propose that second-order nonlinear magnetostriction, where the strain is induced by a second-order magnetic field, is one of the experimental setups to identify the ferroaxial ordering. We show its temperature and magnetic-field-angle dependence by analyzing a fundamental $d$-orbital model under the tetragonal symmetry.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139314787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Taniguchi, Shinnosuke Kitayama, Hirotaka Okabe, Jumpei G. Nakamura, Akihiro Koda, M. Ishikado, Masaki Fujita
We report on the quantum criticality of Pr$_3$Ru$_4$Sn$_{13}$ revealed by our new material research. Pr$_3$Ru$_4$Sn$_{13}$ has been synthesized by flux growth and characterized by single X-ray, powder X-ray, and powder neutron diffraction measurements. The compound adopts a Yb$_3$Rh$_4$Sn$_{13}$-type structure with a cubic Pm$bar{3}$n. From the magnetization at 1 T, the effective magnetic moment was estimated to be 3.58 $mu _B$ per Pr$^{3+}$, suggesting that the magnetism is mainly contributed by Pr$^{3+}$ ions. The specific heat and magnetization show an anomaly at $T_{N} = 7.5$ ~ K owing to the phase transition. The muon spin rotation and relaxation ($mu$SR) time spectra exhibit clear oscillations below $T_N$. This suggests that the phase is magnetically ordered. The volume fraction of the magnetic phase estimated from the initial asymmetry is around ten percent. In addition, spin fluctuations were observed at low temperatures. These results provide microscopic evidence that the material is closest to the antiferromagnetically quantum critical point with a partial order among Pr$_3$$T_4$Sn$_{13}$ ($T= $ Co, Ru, Rh).
我们报告了新材料研究揭示的 Pr$_3$Ru$_4$Sn$_{13}$ 的量子临界性。我们通过通量生长法合成了 Pr$_3$Ru$_4$Sn$_{13}$，并通过单 X 射线、粉末 X 射线和粉末中子衍射测量对其进行了表征。该化合物采用了具有立方 Pm$bar{3}$n 的 Yb$_3$Rh$_4$Sn$_{13}$ 型结构。根据 1 T 时的磁化率估算，每 Pr$^{3+}$ 的有效磁矩为 3.58 $mu _B$，这表明磁性主要来自 Pr$^{3+}$ 离子。由于相变，比热和磁化率在 $T_{N} = 7.5$ ~ K 时出现异常。μ介子自旋旋转和弛豫（$mu$SR）时间谱在低于 $T_N$ 时显示出明显的振荡。这表明该相是磁有序的。根据初始不对称估计，磁性相的体积分数约为百分之十。此外，在低温下也观察到了自旋波动。这些结果提供了微观证据，证明该材料最接近反铁磁量子临界点，在 Pr$_3$T_4$Sn$_{13}$ （$T= $ Co、Ru、Rh）之间存在部分有序。
{"title":"Magnetic Instability of Pr3Ru4Sn13","authors":"T. Taniguchi, Shinnosuke Kitayama, Hirotaka Okabe, Jumpei G. Nakamura, Akihiro Koda, M. Ishikado, Masaki Fujita","doi":"10.7566/jpsj.92.124703","DOIUrl":"https://doi.org/10.7566/jpsj.92.124703","url":null,"abstract":"We report on the quantum criticality of Pr$_3$Ru$_4$Sn$_{13}$ revealed by our new material research. Pr$_3$Ru$_4$Sn$_{13}$ has been synthesized by flux growth and characterized by single X-ray, powder X-ray, and powder neutron diffraction measurements. The compound adopts a Yb$_3$Rh$_4$Sn$_{13}$-type structure with a cubic Pm$bar{3}$n. From the magnetization at 1 T, the effective magnetic moment was estimated to be 3.58 $mu _B$ per Pr$^{3+}$, suggesting that the magnetism is mainly contributed by Pr$^{3+}$ ions. The specific heat and magnetization show an anomaly at $T_{N} = 7.5$ ~ K owing to the phase transition. The muon spin rotation and relaxation ($mu$SR) time spectra exhibit clear oscillations below $T_N$. This suggests that the phase is magnetically ordered. The volume fraction of the magnetic phase estimated from the initial asymmetry is around ten percent. In addition, spin fluctuations were observed at low temperatures. These results provide microscopic evidence that the material is closest to the antiferromagnetically quantum critical point with a partial order among Pr$_3$$T_4$Sn$_{13}$ ($T= $ Co, Ru, Rh).","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139322593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a recent experiment on the interlayer magnetoresistance in the quasi-two-dimensional organic salt, $alpha$-(BEDT-TTF)$_2$I$_3$, it has been observed that at low temperatures, interlayer tunneling attains phase coherence, leading to the emergence of a three-dimensional electronic structure. Theoretically and experimentally it has been suggested that the system exhibits characteristics of a three-dimensional Dirac semimetal as a consequence of broken time-reversal symmetry and inversion symmetry. Here, we perform a theoretical calculation of the magnetoconductivity under an in-plane magnetic field and demonstrate that the system displays a planar Hall effect. Our calculations are based on a realistic model for $alpha$-(BEDT-TTF)$_2$I$_3$ incorporating interlayer tunneling and the tilt of the Dirac cone. Given that the planar Hall effect is anticipated as a consequence of chiral anomaly, our findings provide support for the classification of $alpha$-(BEDT-TTF)$_2$I$_3$ as a three-dimensional Dirac semimetal.
{"title":"Theory for Planar Hall Effect in Organic Dirac Fermion System","authors":"Yuki Nakamura, T. Morinari","doi":"10.7566/JPSJ.92.123701","DOIUrl":"https://doi.org/10.7566/JPSJ.92.123701","url":null,"abstract":"In a recent experiment on the interlayer magnetoresistance in the quasi-two-dimensional organic salt, $alpha$-(BEDT-TTF)$_2$I$_3$, it has been observed that at low temperatures, interlayer tunneling attains phase coherence, leading to the emergence of a three-dimensional electronic structure. Theoretically and experimentally it has been suggested that the system exhibits characteristics of a three-dimensional Dirac semimetal as a consequence of broken time-reversal symmetry and inversion symmetry. Here, we perform a theoretical calculation of the magnetoconductivity under an in-plane magnetic field and demonstrate that the system displays a planar Hall effect. Our calculations are based on a realistic model for $alpha$-(BEDT-TTF)$_2$I$_3$ incorporating interlayer tunneling and the tilt of the Dirac cone. Given that the planar Hall effect is anticipated as a consequence of chiral anomaly, our findings provide support for the classification of $alpha$-(BEDT-TTF)$_2$I$_3$ as a three-dimensional Dirac semimetal.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139322459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate an energy flow in an extended Holstein model describing electron systems coupled to hot-phonons and heat-bath phonons. To analyze the relaxation process after the photo-excitation of electrons, we employ the nonequilibrium dynamical mean-field theory (DMFT). We find the backward energy flow during the relaxation, where the direction of energy transfer between electrons and hot-phonons is reversed. To clarify the microscopic mechanism of the backward energy flow, we introduce the approximated energy flows, which are calculated with the gradient and quasiparticle approximations and are related to the nonequilibrium distribution functions. We compare these approximated energy flows with the full energy flows calculated from the nonequilibrium DMFT. We find that, in the weak electron-hot-phonon coupling regime, the full and approximated energy flows are almost the same, meaning that the relaxation dynamics can be correctly understood in terms of the nonequilibrium distribution functions. As the strength of the electron-hot-phonon coupling increases, the approximated energy flow fails to qualitatively reproduce the full energy flow. This indicates that the microscopic origin of the energy flow cannot be solely explained by the nonequilibrium distribution functions. By comparing the energy flows with different levels of approximation, we reveal the role of the gradient and quasiparticle approximations.
{"title":"Energy Flow during Relaxation in an Electron–Phonon System with Multiple Modes: A Nonequilibrium Green’s Function Study","authors":"Ken Inayoshi, A. Koga, Y. Murakami","doi":"10.7566/jpsj.92.124001","DOIUrl":"https://doi.org/10.7566/jpsj.92.124001","url":null,"abstract":"We investigate an energy flow in an extended Holstein model describing electron systems coupled to hot-phonons and heat-bath phonons. To analyze the relaxation process after the photo-excitation of electrons, we employ the nonequilibrium dynamical mean-field theory (DMFT). We find the backward energy flow during the relaxation, where the direction of energy transfer between electrons and hot-phonons is reversed. To clarify the microscopic mechanism of the backward energy flow, we introduce the approximated energy flows, which are calculated with the gradient and quasiparticle approximations and are related to the nonequilibrium distribution functions. We compare these approximated energy flows with the full energy flows calculated from the nonequilibrium DMFT. We find that, in the weak electron-hot-phonon coupling regime, the full and approximated energy flows are almost the same, meaning that the relaxation dynamics can be correctly understood in terms of the nonequilibrium distribution functions. As the strength of the electron-hot-phonon coupling increases, the approximated energy flow fails to qualitatively reproduce the full energy flow. This indicates that the microscopic origin of the energy flow cannot be solely explained by the nonequilibrium distribution functions. By comparing the energy flows with different levels of approximation, we reveal the role of the gradient and quasiparticle approximations.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139355758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ising machines have the potential to realize fast and highly accurate solvers for combinatorial optimization problems. They are classified based on their internal algorithms. Examples include simulated-annealing-based Ising machines (non-quantum-type Ising machines) and quantum-annealing-based Ising machines (quantum annealers). Herein we propose a hybrid optimization method, which utilizes the advantages of both types. In this hybrid optimization method, the preprocessing step is performed by solving the non-quantum-annealing Ising machine multiple times. Then sub-Ising models with a reduced size by spin fixing are solved using a quantum annealer. The performance of the hybrid optimization method is evaluated via simulations using Simulated Annealing (SA) as a non-quantum-type Ising machine and D-Wave Advantage as a quantum annealer. Additionally, we investigate the parameter dependence of the proposed hybrid optimization method. The hybrid optimization method outperforms the preprocessing SA and the quantum annealing machine alone in fully connected random Ising models.
伊辛机具有为组合优化问题实现快速、高精度求解的潜力。它们根据内部算法进行分类。例如，基于模拟退火的伊辛机（非量子型伊辛机）和基于量子退火的伊辛机（量子退火器）。在这里，我们提出了一种混合优化方法，它利用了这两种方法的优点。在这种混合优化方法中，预处理步骤是多次求解非量子退火伊辛机。然后使用量子退火器求解通过自旋固定缩小尺寸的子伊辛模型。通过使用模拟退火（SA）作为非量子型伊辛机和 D-Wave Advantage 作为量子退火器进行模拟，评估了混合优化方法的性能。此外，我们还研究了所提出的混合优化方法的参数依赖性。在全连接随机伊辛模型中，混合优化方法优于预处理 SA 和单独的量子退火机。
{"title":"Hybrid Optimization Method Using Simulated-Annealing-Based Ising Machine and Quantum Annealer","authors":"Shuta Kikuchi, N. Togawa, Shu Tanaka","doi":"10.7566/JPSJ.92.124002","DOIUrl":"https://doi.org/10.7566/JPSJ.92.124002","url":null,"abstract":"Ising machines have the potential to realize fast and highly accurate solvers for combinatorial optimization problems. They are classified based on their internal algorithms. Examples include simulated-annealing-based Ising machines (non-quantum-type Ising machines) and quantum-annealing-based Ising machines (quantum annealers). Herein we propose a hybrid optimization method, which utilizes the advantages of both types. In this hybrid optimization method, the preprocessing step is performed by solving the non-quantum-annealing Ising machine multiple times. Then sub-Ising models with a reduced size by spin fixing are solved using a quantum annealer. The performance of the hybrid optimization method is evaluated via simulations using Simulated Annealing (SA) as a non-quantum-type Ising machine and D-Wave Advantage as a quantum annealer. Additionally, we investigate the parameter dependence of the proposed hybrid optimization method. The hybrid optimization method outperforms the preprocessing SA and the quantum annealing machine alone in fully connected random Ising models.","PeriodicalId":509167,"journal":{"name":"Journal of the Physical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139370337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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