{"title":"Nonlinear optical response in superconductors in magnetic field: Quantum geometry and topological superconductivity","authors":"Hiroto Tanaka, Hikaru Watanabe, Youichi Yanase","doi":"10.1103/physrevb.110.014520","DOIUrl":null,"url":null,"abstract":"Noncentrosymmetric superconductors offer fascinating phenomena of quantum transport and optics such as nonreciprocal and nonlinear responses. Time-reversal symmetry breaking often plays an essential role in the emergence and enhancement of nonreciprocal transport. In this paper, we show the nonreciprocal optical responses in noncentrosymmetric superconductors arising from time-reversal symmetry breaking by demonstrating them in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>s</mi></math>-wave superconductors with a Rashba spin-orbit coupling and a magnetic field. Numerical results reveal the superconductivity-induced bulk photocurrent and second harmonic generation, which are forbidden at the zero magnetic field. We discuss the properties and mechanisms of the superconducting nonlinear responses emerging under the magnetic field. In particular, we investigate the magnetic field dependence of the photocurrent conductivity and clarify the essential ingredients, which give a contribution unique to superconductors under the magnetic field. This contribution is dominant in the low-carrier-density regime although the corresponding joint density of state is tiny. We attribute the enhancement to the quantum geometry. Moreover, the nonlinear conductivity shows peculiar sign reversal at the transition to the topological superconducting state. We propose a bulk probe of topological transition and quantum geometry in superconductors.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7000,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physical Review B","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1103/physrevb.110.014520","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Physics and Astronomy","Score":null,"Total":0}
引用次数: 0
Abstract
Noncentrosymmetric superconductors offer fascinating phenomena of quantum transport and optics such as nonreciprocal and nonlinear responses. Time-reversal symmetry breaking often plays an essential role in the emergence and enhancement of nonreciprocal transport. In this paper, we show the nonreciprocal optical responses in noncentrosymmetric superconductors arising from time-reversal symmetry breaking by demonstrating them in -wave superconductors with a Rashba spin-orbit coupling and a magnetic field. Numerical results reveal the superconductivity-induced bulk photocurrent and second harmonic generation, which are forbidden at the zero magnetic field. We discuss the properties and mechanisms of the superconducting nonlinear responses emerging under the magnetic field. In particular, we investigate the magnetic field dependence of the photocurrent conductivity and clarify the essential ingredients, which give a contribution unique to superconductors under the magnetic field. This contribution is dominant in the low-carrier-density regime although the corresponding joint density of state is tiny. We attribute the enhancement to the quantum geometry. Moreover, the nonlinear conductivity shows peculiar sign reversal at the transition to the topological superconducting state. We propose a bulk probe of topological transition and quantum geometry in superconductors.
非中心对称超导体具有迷人的量子传输和光学现象,例如非互惠和非线性响应。在非互惠输运的出现和增强过程中,时间反向对称破缺往往起着至关重要的作用。在本文中,我们通过在具有拉什巴自旋轨道耦合和磁场的 s 波超导体中演示由时间反向对称性破缺引起的非互易光学响应。数值结果揭示了超导性诱导的体光电流和二次谐波生成,它们在零磁场下是被禁止的。我们讨论了磁场下出现的超导非线性响应的特性和机制。特别是,我们研究了光电流传导性的磁场依赖性,并阐明了在磁场下超导体特有的基本成分。虽然相应的联合状态密度很小,但这种贡献在低载流子密度体系中占主导地位。我们将这种增强归因于量子几何。此外,在过渡到拓扑超导态时,非线性电导率显示出奇特的符号反转。我们提出了超导体中拓扑转变和量子几何的体探测器。
期刊介绍:
Physical Review B (PRB) is the world’s largest dedicated physics journal, publishing approximately 100 new, high-quality papers each week. The most highly cited journal in condensed matter physics, PRB provides outstanding depth and breadth of coverage, combined with unrivaled context and background for ongoing research by scientists worldwide.
PRB covers the full range of condensed matter, materials physics, and related subfields, including:
-Structure and phase transitions
-Ferroelectrics and multiferroics
-Disordered systems and alloys
-Magnetism
-Superconductivity
-Electronic structure, photonics, and metamaterials
-Semiconductors and mesoscopic systems
-Surfaces, nanoscience, and two-dimensional materials
-Topological states of matter