We investigate some possible symmetries of the superconducting state that emerges in three-dimensional altermagnets in the presence of spin-orbit coupling. We demonstrate within a weak-coupling approach that altermagnetic fluctuations with form factor $boldsymbol{g}_{mathbf{k}}$ promote spin-triplet superconductivity described by gap functions $boldsymbol{d}(mathbf{k}) = boldsymbol{u}(mathbf{k}) times boldsymbol{g}_{mathbf{k}}$, such that $boldsymbol{u}(mathbf{k}) = - boldsymbol{u}(-mathbf{k})$. Consequently, this singles out $f$-wave spin-triplet superconductivity as the most favorable pairing state to appear in the vicinity of $d$-wave altermagnetism. Furthermore, we obtain that the combination of spin-singlet superconducting states with altermagnetism gives rise to Bogoliubov-Fermi surfaces, which are protected by a $mathbb{Z}_2$ topological invariant. Using a Ginzburg-Landau analysis, we show that, for a class of spin-orbit coupled altermagnetic models, a superconducting phase is expected to appear at low temperatures as an intertwined $d + if$ state, thus breaking time-reversal symmetry spontaneously.
{"title":"Unconventional superconductivity in altermagnets with spin-orbit coupling","authors":"Vanuildo S. de Carvalho, Hermann Freire","doi":"arxiv-2409.10712","DOIUrl":"https://doi.org/arxiv-2409.10712","url":null,"abstract":"We investigate some possible symmetries of the superconducting state that\u0000emerges in three-dimensional altermagnets in the presence of spin-orbit\u0000coupling. We demonstrate within a weak-coupling approach that altermagnetic\u0000fluctuations with form factor $boldsymbol{g}_{mathbf{k}}$ promote\u0000spin-triplet superconductivity described by gap functions\u0000$boldsymbol{d}(mathbf{k}) = boldsymbol{u}(mathbf{k}) times\u0000boldsymbol{g}_{mathbf{k}}$, such that $boldsymbol{u}(mathbf{k}) = -\u0000boldsymbol{u}(-mathbf{k})$. Consequently, this singles out $f$-wave\u0000spin-triplet superconductivity as the most favorable pairing state to appear in\u0000the vicinity of $d$-wave altermagnetism. Furthermore, we obtain that the\u0000combination of spin-singlet superconducting states with altermagnetism gives\u0000rise to Bogoliubov-Fermi surfaces, which are protected by a $mathbb{Z}_2$\u0000topological invariant. Using a Ginzburg-Landau analysis, we show that, for a\u0000class of spin-orbit coupled altermagnetic models, a superconducting phase is\u0000expected to appear at low temperatures as an intertwined $d + if$ state, thus\u0000breaking time-reversal symmetry spontaneously.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253509","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}
Kristen W. Léonard, Anton V. Bubis, Melissa Mikalsen, William F. Schiela, Bassel H. Elfeky, Duc Phan, Javad Shabani, Andrew P. Higginbotham
Anomalous metallic behavior is ubiquitously observed near superconductor-insulator quantum critical points and, if persistent to zero temperature, poses a challenge to current theories of metals. One explanation for this behavior could be incomplete thermal equilibrium between the sample and the cryostat. However, despite decades of study, the actual temperature of an anomalous metallic sample has not been measured. We therefore introduce a new experimental probe by measuring microwave radiation emitted from the anomalous metal, using a two-dimensional array of superconductor-semiconductor hybrid Josephson junctions as a model system. The total emitted radiation exceeds the limits of thermodynamic equilibrium, but is well described by an elevated sample temperature. This extracted sample temperature matches the onset of anomalous metallic behavior. Additionally, we discover scaling behavior of radiative noise in the presence of an applied bias. Elements of our noise-scaling observations were predicted based on nonlinear critical field theories and gauge-gravity duality. This work shows that, in a prominent model system, anomalous metallic behavior is a non-equilibrium effect, and opens a new frontier in the study of universal, non-equilibrium phenomena near quantum criticality.
{"title":"Microwave radiation at criticality in a hybrid Josephson array","authors":"Kristen W. Léonard, Anton V. Bubis, Melissa Mikalsen, William F. Schiela, Bassel H. Elfeky, Duc Phan, Javad Shabani, Andrew P. Higginbotham","doi":"arxiv-2409.09835","DOIUrl":"https://doi.org/arxiv-2409.09835","url":null,"abstract":"Anomalous metallic behavior is ubiquitously observed near\u0000superconductor-insulator quantum critical points and, if persistent to zero\u0000temperature, poses a challenge to current theories of metals. One explanation\u0000for this behavior could be incomplete thermal equilibrium between the sample\u0000and the cryostat. However, despite decades of study, the actual temperature of\u0000an anomalous metallic sample has not been measured. We therefore introduce a\u0000new experimental probe by measuring microwave radiation emitted from the\u0000anomalous metal, using a two-dimensional array of superconductor-semiconductor\u0000hybrid Josephson junctions as a model system. The total emitted radiation\u0000exceeds the limits of thermodynamic equilibrium, but is well described by an\u0000elevated sample temperature. This extracted sample temperature matches the\u0000onset of anomalous metallic behavior. Additionally, we discover scaling\u0000behavior of radiative noise in the presence of an applied bias. Elements of our\u0000noise-scaling observations were predicted based on nonlinear critical field\u0000theories and gauge-gravity duality. This work shows that, in a prominent model\u0000system, anomalous metallic behavior is a non-equilibrium effect, and opens a\u0000new frontier in the study of universal, non-equilibrium phenomena near quantum\u0000criticality.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253516","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 introduce a class of topological pairing orders characterized by a half-integer pair monopole charge, leading to Berry phase enforced half-integer partial wave symmetry. This exotic spinor order emerges from pairing between Fermi surfaces with Chern numbers differing by an odd integer. Using tight-binding models, we demonstrate spinor superconducting orders with monopole charges $pm 1/2$, featuring a single gap node and nontrivial surface states. Additionally, the superfluid velocity follows a fractionalized Mermin-Ho relation in spatially inhomogeneous pairing orders. The concept extends to spinor density waves and excitons.
{"title":"Berry Phase Enforced Spinor Pairing Order","authors":"Yi Li, Grayson R. Frazier","doi":"arxiv-2409.09579","DOIUrl":"https://doi.org/arxiv-2409.09579","url":null,"abstract":"We introduce a class of topological pairing orders characterized by a\u0000half-integer pair monopole charge, leading to Berry phase enforced half-integer\u0000partial wave symmetry. This exotic spinor order emerges from pairing between\u0000Fermi surfaces with Chern numbers differing by an odd integer. Using\u0000tight-binding models, we demonstrate spinor superconducting orders with\u0000monopole charges $pm 1/2$, featuring a single gap node and nontrivial surface\u0000states. Additionally, the superfluid velocity follows a fractionalized\u0000Mermin-Ho relation in spatially inhomogeneous pairing orders. The concept\u0000extends to spinor density waves and excitons.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253511","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}
Various clathrate superhydride superconductors have been found to possess hydrogen deficiency in experimental samples, while their impacts on superconductivity are often neglected. In this study, we investigate the superconductivity of lanthanum superhydride with hydrogen deficiency (LaH$_{10-delta}$) from first principles using path-integral approaches. Under the effects of thermal and quantum fluctuations, hydrogen vacancies are found to diffuse within the system, leading to modifications in ion vibrations, electronic structure and electron-phonon coupling. These changes result in a non-monotonic dependence of superconducting transition temperature ($T_c$) on the vacancy concentration ($delta$). By comparing the experimental and theoretical equations of state, we suggest that $delta$ varies across samples under different pressures. This explains the positive pressure dependence of $T_c$ in experiments below 150 GPa. Remarkably, within this pressure range, we find that $T_c$ could be further raised by increasing $delta$.
{"title":"Enhancing superconducting transition temperature of lanthanum superhydride by increasing hydrogen vacancy concentration","authors":"Haoran Chen, Hui Wang, Junren Shi","doi":"arxiv-2409.09836","DOIUrl":"https://doi.org/arxiv-2409.09836","url":null,"abstract":"Various clathrate superhydride superconductors have been found to possess\u0000hydrogen deficiency in experimental samples, while their impacts on\u0000superconductivity are often neglected. In this study, we investigate the\u0000superconductivity of lanthanum superhydride with hydrogen deficiency\u0000(LaH$_{10-delta}$) from first principles using path-integral approaches. Under\u0000the effects of thermal and quantum fluctuations, hydrogen vacancies are found\u0000to diffuse within the system, leading to modifications in ion vibrations,\u0000electronic structure and electron-phonon coupling. These changes result in a\u0000non-monotonic dependence of superconducting transition temperature ($T_c$) on\u0000the vacancy concentration ($delta$). By comparing the experimental and\u0000theoretical equations of state, we suggest that $delta$ varies across samples\u0000under different pressures. This explains the positive pressure dependence of\u0000$T_c$ in experiments below 150 GPa. Remarkably, within this pressure range, we\u0000find that $T_c$ could be further raised by increasing $delta$.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253510","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}
Zizhong Li, Apoorv Jindal, Alex Strasser, Yangchen He, Wenkai Zheng, David Graf, Takashi Taniguchi, Kenji Watanabe, Luis Balicas, Cory R. Dean, Xiaofeng Qian, Abhay N. Pasupathy, Daniel A. Rhodes
Noncentrosymmetric 2D superconductors with large spin-orbit coupling offer an opportunity to explore superconducting behaviors far beyond the Pauli limit. One such superconductor, few-layer T$_d$-MoTe$_2$, has large upper critical fields that can exceed the Pauli limit by up to 600%. However, the mechanisms governing this enhancement are still under debate, with theory pointing towards either spin-orbit parity coupling or tilted Ising spin-orbit coupling. Moreover, ferroelectricity concomitant with superconductivity has been recently observed in the bilayer, where strong changes to superconductivity can be observed throughout the ferroelectric transition pathway. Here, we report the superconducting behavior of bilayer T$_d$-MoTe$ _2$ under an in-plane magnetic field, while systematically varying magnetic field angle and out-of-plane electric field strength. We find that superconductivity in bilayer MoTe$_2$ exhibits a two-fold symmetry with an upper critical field maxima occurring along the b-axis and minima along the a-axis. The two-fold rotational symmetry remains robust throughout the entire superconducting region and ferroelectric hysteresis loop. Our experimental observations of the spin-orbit coupling strength (up to 16.4 meV) agree with the spin texture and spin splitting from first-principles calculations, indicating that tilted Ising spin-orbit coupling is the dominant underlying mechanism.
具有大自旋轨道耦合的非五次对称二维超导体为探索远超过保利极限的超导行为提供了机会。其中一种超导体--少层 T$_d$-MoTe$_2$ 具有大临界上场，可超过保利极限达 600%。此外，最近还在双电层中观察到了与超导性同时存在的铁电性，在整个铁电转换途径中都可以观察到超导性的强烈变化。在这里，我们报告了双电层 T$_d$-MoTe$ _2$在平面内磁场下的超导行为，同时系统地改变了磁场角度和平面外电场强度。我们发现，双层 MoTe$_2$ 中的超导现象具有两重对称性，上临界磁场最大值沿 b 轴出现，最小值沿 a 轴出现。在整个超导区域和铁电磁滞回线中，这种二重旋转对称性始终保持稳固。我们对自旋轨道耦合强度（高达 16.4 meV）的实验观察结果与第一原理计算得出的自旋纹理和自旋分裂一致，表明倾斜伊辛自旋轨道耦合是主要的基本机制。
{"title":"Two-Fold Anisotropic Superconductivity in Bilayer T$_d$-MoTe$_2$","authors":"Zizhong Li, Apoorv Jindal, Alex Strasser, Yangchen He, Wenkai Zheng, David Graf, Takashi Taniguchi, Kenji Watanabe, Luis Balicas, Cory R. Dean, Xiaofeng Qian, Abhay N. Pasupathy, Daniel A. Rhodes","doi":"arxiv-2409.09308","DOIUrl":"https://doi.org/arxiv-2409.09308","url":null,"abstract":"Noncentrosymmetric 2D superconductors with large spin-orbit coupling offer an\u0000opportunity to explore superconducting behaviors far beyond the Pauli limit.\u0000One such superconductor, few-layer T$_d$-MoTe$_2$, has large upper critical\u0000fields that can exceed the Pauli limit by up to 600%. However, the mechanisms\u0000governing this enhancement are still under debate, with theory pointing towards\u0000either spin-orbit parity coupling or tilted Ising spin-orbit coupling.\u0000Moreover, ferroelectricity concomitant with superconductivity has been recently\u0000observed in the bilayer, where strong changes to superconductivity can be\u0000observed throughout the ferroelectric transition pathway. Here, we report the\u0000superconducting behavior of bilayer T$_d$-MoTe$ _2$ under an in-plane magnetic\u0000field, while systematically varying magnetic field angle and out-of-plane\u0000electric field strength. We find that superconductivity in bilayer MoTe$_2$\u0000exhibits a two-fold symmetry with an upper critical field maxima occurring\u0000along the b-axis and minima along the a-axis. The two-fold rotational symmetry\u0000remains robust throughout the entire superconducting region and ferroelectric\u0000hysteresis loop. Our experimental observations of the spin-orbit coupling\u0000strength (up to 16.4 meV) agree with the spin texture and spin splitting from\u0000first-principles calculations, indicating that tilted Ising spin-orbit coupling\u0000is the dominant underlying mechanism.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"187 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253515","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}
Tengdong Zhang, Chenyu Suo, Yanling Wu, Xiaodan Xu, Yong Liu, Dao-Xin Yao, Jun Li
In comparison to simpler data such as chemical formulas and lattice structures, electronic band structure data provide a more fundamental and intuitive insight into superconducting phenomena. In this work, we generate superconductor's lattice structure files optimized for density functional theory (DFT) calculations. Through DFT, we obtain electronic band superconductors, including band structures, density of states (DOS), and Fermi surface data. Additionally, we outline efficient methodologies for acquiring structure data, establish high-throughput DFT computational protocols, and introduce tools for extracting this data from large-scale DFT calculations. As an example, we have curated a dataset containing information on 2474 superconductors along with their experimentally determined superconducting transition temperatures, which is well-suited for machine learning applications. This work also provides guidelines for accessing and utilizing this dataset. Furthermore, we present a neural network model designed for training with this data. All the aforementioned data and code are publicly available at http://www.superband.work.
{"title":"Superband: an Electronic-band and Fermi surface structure database of superconductors","authors":"Tengdong Zhang, Chenyu Suo, Yanling Wu, Xiaodan Xu, Yong Liu, Dao-Xin Yao, Jun Li","doi":"arxiv-2409.09419","DOIUrl":"https://doi.org/arxiv-2409.09419","url":null,"abstract":"In comparison to simpler data such as chemical formulas and lattice\u0000structures, electronic band structure data provide a more fundamental and\u0000intuitive insight into superconducting phenomena. In this work, we generate\u0000superconductor's lattice structure files optimized for density functional\u0000theory (DFT) calculations. Through DFT, we obtain electronic band\u0000superconductors, including band structures, density of states (DOS), and Fermi\u0000surface data. Additionally, we outline efficient methodologies for acquiring\u0000structure data, establish high-throughput DFT computational protocols, and\u0000introduce tools for extracting this data from large-scale DFT calculations. As\u0000an example, we have curated a dataset containing information on 2474\u0000superconductors along with their experimentally determined superconducting\u0000transition temperatures, which is well-suited for machine learning\u0000applications. This work also provides guidelines for accessing and utilizing\u0000this dataset. Furthermore, we present a neural network model designed for\u0000training with this data. All the aforementioned data and code are publicly\u0000available at http://www.superband.work.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253513","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 examine various possibilities for the pairing mechanisms in the recently discovered bilayer-nickelate superconductor within the Bardeen-Cooper-Schrieffer framework. Unlike earlier studies, where only a pure $d$-wave or sign-changing $s$-wave superconductivity instability was investigated, our study explores the possibilities of mixed-state superconducting instability such as the one involving both $d$- and sign-changing $s$-waves. While assuming that the superconductivity arises because of the magnetic correlations, we examine the nature of the superconducting gap function associated density of states with various possible magnetic correlation wavevectors arising out as a result of multiple pockets owing to the multiple orbitals and bilayer splitting. We also explore the effect of differences in the nature of Fermi surfaces suggested by various studies.
{"title":"Possible pairing states in the superconducting bilayer nickelate","authors":"Dheeraj Kumar Singh, Garima Goyal, Yunkyu Bang","doi":"arxiv-2409.09321","DOIUrl":"https://doi.org/arxiv-2409.09321","url":null,"abstract":"We examine various possibilities for the pairing mechanisms in the recently\u0000discovered bilayer-nickelate superconductor within the\u0000Bardeen-Cooper-Schrieffer framework. Unlike earlier studies, where only a pure\u0000$d$-wave or sign-changing $s$-wave superconductivity instability was\u0000investigated, our study explores the possibilities of mixed-state\u0000superconducting instability such as the one involving both $d$- and\u0000sign-changing $s$-waves. While assuming that the superconductivity arises\u0000because of the magnetic correlations, we examine the nature of the\u0000superconducting gap function associated density of states with various possible\u0000magnetic correlation wavevectors arising out as a result of multiple pockets\u0000owing to the multiple orbitals and bilayer splitting. We also explore the\u0000effect of differences in the nature of Fermi surfaces suggested by various\u0000studies.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"206 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253512","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}
M. C. Diamantini, C. A. Trugenberger, V. M. Vinokur
Traditional superconductors fall into two categories, type-I, expelling magnetic fields, and type-II, into which magnetic fields exceeding a lower critical field $H_{rm c1}$ penetrate in form of Abrikosov vortices. Abrikosov vortices are characterized by two spatial scales, the size of the normal core, $xi$, where the superconducting order parameter is suppressed and the London penetration depth $lambda$, describing the scale at which circulating superconducting currents forming vortices start to noticeably drop. Here we demonstrate that a novel type-III superconductivity, realized in granular media in any dimension hosts a novel vortex physics. Type-III vortices have no cores, are logarithmically confined and carry only a gauge scale $lambda$. Accordingly, in type-III superconductors $H_{rm c1}=0$ at zero temperature and the Ginzburg-Landau theory must be replaced by a topological gauge theory. Type-III superconductivity is destroyed not by Cooper pair breaking but by vortex proliferation generalizing the Berezinskii-Kosterlitz-Thouless mechanism to any dimension.
{"title":"Topological gauge theory of vortices in type-III superconductors","authors":"M. C. Diamantini, C. A. Trugenberger, V. M. Vinokur","doi":"arxiv-2409.08866","DOIUrl":"https://doi.org/arxiv-2409.08866","url":null,"abstract":"Traditional superconductors fall into two categories, type-I, expelling\u0000magnetic fields, and type-II, into which magnetic fields exceeding a lower\u0000critical field $H_{rm c1}$ penetrate in form of Abrikosov vortices. Abrikosov\u0000vortices are characterized by two spatial scales, the size of the normal core,\u0000$xi$, where the superconducting order parameter is suppressed and the London\u0000penetration depth $lambda$, describing the scale at which circulating\u0000superconducting currents forming vortices start to noticeably drop. Here we\u0000demonstrate that a novel type-III superconductivity, realized in granular media\u0000in any dimension hosts a novel vortex physics. Type-III vortices have no cores,\u0000are logarithmically confined and carry only a gauge scale $lambda$.\u0000Accordingly, in type-III superconductors $H_{rm c1}=0$ at zero temperature and\u0000the Ginzburg-Landau theory must be replaced by a topological gauge theory.\u0000Type-III superconductivity is destroyed not by Cooper pair breaking but by\u0000vortex proliferation generalizing the Berezinskii-Kosterlitz-Thouless mechanism\u0000to any dimension.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"206 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253518","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 theoretically study the finite-momentum superconductivity in two-dimensional (2D) altermagnets with a Rashba-type spin-orbit coupling (RSOC). We show the phase diagrams obtained by solving the linearized gap equation. We consider two directions of the N'{e}el vector of the 2D altermagnet: parallel to the $x$-$y$ plane (in-plane) and perpendicular to the $x$-$y$ plane (out-of-plane). For the in-plane N'{e}el vector, we find two different finite-momentum $d_{x^2-y^2}$-wave superconducting states distinguished by a dominant pairing channel: the inter-band pairing or the intra-band pairing. Furthermore, it is shown that an asymmetric deformation of Fermi surfaces caused by spin-splitting effects due to the in-plane altermagnet and the RSOC stabilizes the finite-momentum superconductivity with a large band splitting. For the out-of-plane N'{e}el vector, the finite-momentum superconductivity is found only in the inter-band pairing mechanism, which is in contrast to the in-plane case.
{"title":"Finite-momentum superconductivity in two-dimensional altermagnets with a Rashba-type spin-orbit coupling","authors":"Kohei Mukasa, Yusuke Masaki","doi":"arxiv-2409.08972","DOIUrl":"https://doi.org/arxiv-2409.08972","url":null,"abstract":"We theoretically study the finite-momentum superconductivity in\u0000two-dimensional (2D) altermagnets with a Rashba-type spin-orbit coupling\u0000(RSOC). We show the phase diagrams obtained by solving the linearized gap\u0000equation. We consider two directions of the N'{e}el vector of the 2D\u0000altermagnet: parallel to the $x$-$y$ plane (in-plane) and perpendicular to the\u0000$x$-$y$ plane (out-of-plane). For the in-plane N'{e}el vector, we find two\u0000different finite-momentum $d_{x^2-y^2}$-wave superconducting states\u0000distinguished by a dominant pairing channel: the inter-band pairing or the\u0000intra-band pairing. Furthermore, it is shown that an asymmetric deformation of\u0000Fermi surfaces caused by spin-splitting effects due to the in-plane altermagnet\u0000and the RSOC stabilizes the finite-momentum superconductivity with a large band\u0000splitting. For the out-of-plane N'{e}el vector, the finite-momentum\u0000superconductivity is found only in the inter-band pairing mechanism, which is\u0000in contrast to the in-plane case.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253517","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}
Chun Yu Wan, Yujun Zhao, Yaoyi Li, Jinfeng Jia, Junwei Liu
Topological crystalline insulators are known to support multiple Majorana zero modes (MZMs) at a single vortex, their hybridization is forbidden by a magnetic mirror symmetry $M_T$. Due to the limited energy resolution of scanning tunneling microscopes and the very small energy spacing of trivial bound states, it remains challenging to directly probe and demonstrate the existence of multiple MZMs. In this work, we propose to demonstrate the existence of MZMs by studying the hybridization of multiple MZMs in a symmetry breaking field. The different responses of trivial bound states and MZMs can be inferred from their spatial distribution in the vortex. However, the theoretical simulations are very demanding since it requires an extremely large system in real space. By utilizing the kernel polynomial method, we can efficiently simulate large lattices with over $10^8$ orbitals to compute the local density of states which bridges the gap between theoretical studies based on minimal models and experimental measurements. We show that the spatial distribution of MZMs and trivial vortex bound states indeed differs drastically in tilted magnetic fields. The zero-bias peak elongates when the magnetic field preserves $M_T$, while it splits when $M_T$ is broken, giving rise to an anisotropic magnetic response. Since the bulk of SnTe are metallic, we also study the robustness of MZMs against the bulk states, and clarify when can the MZMs produce a pronounced anisotropic magnetic response.
{"title":"Large-scale simulations of vortex Majorana zero modes in topological crystalline insulators","authors":"Chun Yu Wan, Yujun Zhao, Yaoyi Li, Jinfeng Jia, Junwei Liu","doi":"arxiv-2409.08683","DOIUrl":"https://doi.org/arxiv-2409.08683","url":null,"abstract":"Topological crystalline insulators are known to support multiple Majorana\u0000zero modes (MZMs) at a single vortex, their hybridization is forbidden by a\u0000magnetic mirror symmetry $M_T$. Due to the limited energy resolution of\u0000scanning tunneling microscopes and the very small energy spacing of trivial\u0000bound states, it remains challenging to directly probe and demonstrate the\u0000existence of multiple MZMs. In this work, we propose to demonstrate the\u0000existence of MZMs by studying the hybridization of multiple MZMs in a symmetry\u0000breaking field. The different responses of trivial bound states and MZMs can be\u0000inferred from their spatial distribution in the vortex. However, the\u0000theoretical simulations are very demanding since it requires an extremely large\u0000system in real space. By utilizing the kernel polynomial method, we can\u0000efficiently simulate large lattices with over $10^8$ orbitals to compute the\u0000local density of states which bridges the gap between theoretical studies based\u0000on minimal models and experimental measurements. We show that the spatial\u0000distribution of MZMs and trivial vortex bound states indeed differs drastically\u0000in tilted magnetic fields. The zero-bias peak elongates when the magnetic field\u0000preserves $M_T$, while it splits when $M_T$ is broken, giving rise to an\u0000anisotropic magnetic response. Since the bulk of SnTe are metallic, we also\u0000study the robustness of MZMs against the bulk states, and clarify when can the\u0000MZMs produce a pronounced anisotropic magnetic response.","PeriodicalId":501069,"journal":{"name":"arXiv - PHYS - Superconductivity","volume":"207 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268812","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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