Pub Date : 2025-03-06DOI: 10.1103/physrevb.111.115119
Cristian Voinea, Songyang Pu, Ajit C. Balram, Zlatko Papić
The composite fermion Fermi liquid (CFL) state at ν=1/2 filling of a Landau level is a paradigmatic non-Fermi liquid borne out purely by Coulomb interactions. But in what ways is this exotic state of matter different from a Fermi liquid? The CFL entanglement entropy was indeed found to exhibit a significant enhancement compared to free electrons [J. Shao , ], which was subsequently ruled out as a finite-size effect by the study of a lattice CFL analog [R. V. Mishmash and O. I. Motrunich, ]. Moreover, the enhancement was not observed in a quasi-one-dimensional limit of the Coulomb ground state at ν=1/2 [S. D. Geraedts , ]. Here, we revisit the problem of entanglement scaling in the CFL state realized in a two-dimensional electron gas. Using Monte Carlo evaluation of the second Rényi entropy S2 for the CFL variational wave function, we show that the entanglement enhancement is present not only at ν=1/2, but also at ν=1/4, as well as in bosonic CFL states at ν=1 and ν=1/3 fillings. In all cases, we find the scaling of S2 with subsystem size to be enhanced compared to the noninteracting case, and insensitive to the choice of geometry and projection to the lowest Landau level. We also demonstrate that for CFL states, the variance of the particle number in a subsystem obeys area-law scaling with a universal subleading corner contribution, in stark contrast with free fermions. Our results establish the enhanced entanglement scaling and suppressed charge fluctuations as fingerprints of non-Fermi-liquid correlations in CFL states. Published by the American Physical Society2025
{"title":"Entanglement scaling and charge fluctuations in a Fermi liquid of composite fermions","authors":"Cristian Voinea, Songyang Pu, Ajit C. Balram, Zlatko Papić","doi":"10.1103/physrevb.111.115119","DOIUrl":"https://doi.org/10.1103/physrevb.111.115119","url":null,"abstract":"The composite fermion Fermi liquid (CFL) state at ν</a:mi>=</a:mo>1</a:mn>/</a:mo>2</a:mn></a:mrow></a:math> filling of a Landau level is a paradigmatic non-Fermi liquid borne out purely by Coulomb interactions. But in what ways is this exotic state of matter different from a Fermi liquid? The CFL entanglement entropy was indeed found to exhibit a significant enhancement compared to free electrons [J. Shao , ], which was subsequently ruled out as a finite-size effect by the study of a lattice CFL analog [R. V. Mishmash and O. I. Motrunich, ]. Moreover, the enhancement was not observed in a quasi-one-dimensional limit of the Coulomb ground state at <b:math xmlns:b=\"http://www.w3.org/1998/Math/MathML\"><b:mrow><b:mi>ν</b:mi><b:mo>=</b:mo><b:mn>1</b:mn><b:mo>/</b:mo><b:mn>2</b:mn></b:mrow></b:math> [S. D. Geraedts , ]. Here, we revisit the problem of entanglement scaling in the CFL state realized in a two-dimensional electron gas. Using Monte Carlo evaluation of the second Rényi entropy <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\"><c:msub><c:mi>S</c:mi><c:mn>2</c:mn></c:msub></c:math> for the CFL variational wave function, we show that the entanglement enhancement is present not only at <d:math xmlns:d=\"http://www.w3.org/1998/Math/MathML\"><d:mrow><d:mi>ν</d:mi><d:mo>=</d:mo><d:mn>1</d:mn><d:mo>/</d:mo><d:mn>2</d:mn></d:mrow></d:math>, but also at <e:math xmlns:e=\"http://www.w3.org/1998/Math/MathML\"><e:mrow><e:mi>ν</e:mi><e:mo>=</e:mo><e:mn>1</e:mn><e:mo>/</e:mo><e:mn>4</e:mn></e:mrow></e:math>, as well as in bosonic CFL states at <f:math xmlns:f=\"http://www.w3.org/1998/Math/MathML\"><f:mrow><f:mi>ν</f:mi><f:mo>=</f:mo><f:mn>1</f:mn></f:mrow></f:math> and <g:math xmlns:g=\"http://www.w3.org/1998/Math/MathML\"><g:mrow><g:mi>ν</g:mi><g:mo>=</g:mo><g:mn>1</g:mn><g:mo>/</g:mo><g:mn>3</g:mn></g:mrow></g:math> fillings. In all cases, we find the scaling of <h:math xmlns:h=\"http://www.w3.org/1998/Math/MathML\"><h:msub><h:mi>S</h:mi><h:mn>2</h:mn></h:msub></h:math> with subsystem size to be enhanced compared to the noninteracting case, and insensitive to the choice of geometry and projection to the lowest Landau level. We also demonstrate that for CFL states, the variance of the particle number in a subsystem obeys area-law scaling with a universal subleading corner contribution, in stark contrast with free fermions. Our results establish the enhanced entanglement scaling and suppressed charge fluctuations as fingerprints of non-Fermi-liquid correlations in CFL states. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"7 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143569632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1103/physrevb.111.115110
David Gunn, Georgios Styliaris, Tristan Kraft, Barbara Kraus
Two matrix product states (MPS) are in the same phase in the presence of symmetries if they can be transformed into one another via symmetric short-depth circuits. We consider how symmetry-preserving measurements with feedforward alter the phase classification of MPS in the presence of global on-site symmetries. We demonstrate that, for all finite Abelian symmetries, any two symmetric MPS belong to the same phase. We give an explicit protocol that achieves a transformation between any two phases and that uses only a depth-two symmetric circuit, a single round of symmetric measurements, and a constant number of auxiliary systems per site. In the case of non-Abelian symmetries, symmetry protection prevents one from deterministically transforming symmetry-protected topological (SPT) states to product states directly via measurements, thereby complicating the analysis. Nonetheless, we provide protocols that allow for asymptotically deterministic transformations between the trivial phase, SPT phases, and GHZ phases of some non-Abelian nilpotent groups. Published by the American Physical Society2025
{"title":"Phases of matrix product states with symmetric quantum circuits and symmetric measurements with feedforward","authors":"David Gunn, Georgios Styliaris, Tristan Kraft, Barbara Kraus","doi":"10.1103/physrevb.111.115110","DOIUrl":"https://doi.org/10.1103/physrevb.111.115110","url":null,"abstract":"Two matrix product states (MPS) are in the same phase in the presence of symmetries if they can be transformed into one another via symmetric short-depth circuits. We consider how symmetry-preserving measurements with feedforward alter the phase classification of MPS in the presence of global on-site symmetries. We demonstrate that, for all finite Abelian symmetries, any two symmetric MPS belong to the same phase. We give an explicit protocol that achieves a transformation between any two phases and that uses only a depth-two symmetric circuit, a single round of symmetric measurements, and a constant number of auxiliary systems per site. In the case of non-Abelian symmetries, symmetry protection prevents one from deterministically transforming symmetry-protected topological (SPT) states to product states directly via measurements, thereby complicating the analysis. Nonetheless, we provide protocols that allow for asymptotically deterministic transformations between the trivial phase, SPT phases, and GHZ phases of some non-Abelian nilpotent groups. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"12 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143569634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1103/physrevb.111.104301
Andrei I. Pavlov, Yuval Gefen, Alexander Shnirman
Complex spectra of dissipative quantum systems may exhibit degeneracies known as exceptional points (EPs). At these points the systems' dynamics may undergo drastic changes. Phenomena associated with EPs and their applications have been extensively studied in relation to various experimental platforms, including, i.e., the superconducting circuits. While most of the studies focus on EPs appearing due to the variation of the system's physical parameters, we focus on EPs emerging in the full counting statistics of the system. We consider a monitored three-level system and find multiple EPs in the Lindbladian eigenvalues considered as functions of a counting field. These “hidden” EPs are not accessible without the insertion of the counting field into the Linbladian, i.e., if only the density matrix of the system is studied. Nevertheless, we show that the hidden EPs are accessible experimentally. We demonstrate that these EPs signify transitions between different topological classes which are rigorously characterized in terms of the braid theory. Furthermore, we identify dynamical observables affected by these transitions and demonstrate how experimentally measured quantum jump distributions can be used to spot transitions between different topological regimes. Additionally, we establish a duality between the conventional Lindbladian EPs (zero counting field) and some of the “hidden” ones. Our findings allow for easier experimental observations of the EP transitions, normally concealed by the Lindbladian steady state, without applying postselection schemes. These results can be directly generalized to any monitored open system as long as it is described within the Lindbladian formalism. Published by the American Physical Society2025
{"title":"Topological transitions in quantum jump dynamics: Hidden exceptional points","authors":"Andrei I. Pavlov, Yuval Gefen, Alexander Shnirman","doi":"10.1103/physrevb.111.104301","DOIUrl":"https://doi.org/10.1103/physrevb.111.104301","url":null,"abstract":"Complex spectra of dissipative quantum systems may exhibit degeneracies known as exceptional points (EPs). At these points the systems' dynamics may undergo drastic changes. Phenomena associated with EPs and their applications have been extensively studied in relation to various experimental platforms, including, i.e., the superconducting circuits. While most of the studies focus on EPs appearing due to the variation of the system's physical parameters, we focus on EPs emerging in the full counting statistics of the system. We consider a monitored three-level system and find multiple EPs in the Lindbladian eigenvalues considered as functions of a counting field. These “hidden” EPs are not accessible without the insertion of the counting field into the Linbladian, i.e., if only the density matrix of the system is studied. Nevertheless, we show that the hidden EPs are accessible experimentally. We demonstrate that these EPs signify transitions between different topological classes which are rigorously characterized in terms of the braid theory. Furthermore, we identify dynamical observables affected by these transitions and demonstrate how experimentally measured quantum jump distributions can be used to spot transitions between different topological regimes. Additionally, we establish a duality between the conventional Lindbladian EPs (zero counting field) and some of the “hidden” ones. Our findings allow for easier experimental observations of the EP transitions, normally concealed by the Lindbladian steady state, without applying postselection schemes. These results can be directly generalized to any monitored open system as long as it is described within the Lindbladian formalism. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"2 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143569635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-05DOI: 10.1103/physrevb.111.115111
V. Nagorkin, S. Schimmel, P. Gebauer, A. Isaeva, D. Baumann, A. Koitzsch, B. Büchner, C. Hess
We investigated the electronic properties of the topological insulator Bi2Te3 by scanning tunneling microscopy and spectroscopy at low temperature. We obtained high-resolution quasiparticle interference data of the topological surface Dirac electrons at different energies. Spin-selective joint density of states calculations were performed for surface and bulk electronic states to interpret the observed quasiparticle interference data. The topological properties of our crystals are demonstrated by the absence of backscattering along with the linear energy dispersion of the dominant scattering vector. In addition, we detect nondispersive scattering modes which we associate with bulk-surface scattering and, thus, allow an approximate identification of the bulk energy gap range based on our quasiparticle interference data. Measurements of differential conductance maps in magnetic fields up to 15 T have been carried out, but no strong modifications could be observed. Published by the American Physical Society2025
{"title":"Bulk and surface electron scattering in disordered Bi2Te3 probed by quasiparticle interference","authors":"V. Nagorkin, S. Schimmel, P. Gebauer, A. Isaeva, D. Baumann, A. Koitzsch, B. Büchner, C. Hess","doi":"10.1103/physrevb.111.115111","DOIUrl":"https://doi.org/10.1103/physrevb.111.115111","url":null,"abstract":"We investigated the electronic properties of the topological insulator Bi</a:mi>2</a:mn></a:msub>Te</a:mi>3</a:mn></a:msub></a:mrow></a:math> by scanning tunneling microscopy and spectroscopy at low temperature. We obtained high-resolution quasiparticle interference data of the topological surface Dirac electrons at different energies. Spin-selective joint density of states calculations were performed for surface and bulk electronic states to interpret the observed quasiparticle interference data. The topological properties of our crystals are demonstrated by the absence of backscattering along with the linear energy dispersion of the dominant scattering vector. In addition, we detect nondispersive scattering modes which we associate with bulk-surface scattering and, thus, allow an approximate identification of the bulk energy gap range based on our quasiparticle interference data. Measurements of differential conductance maps in magnetic fields up to 15 T have been carried out, but no strong modifications could be observed. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"67 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143569637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-04DOI: 10.1103/physrevb.111.l121101
Guoren Zhang, Hanif Hadipour, Eva Pavarini
At ambient pressure, the t2g5 layered perovskite Sr2IrO4 is a correlated small-gap insulator. In the Mott picture, applying uniform pressure should therefore quickly close the gap; experimentally, however, the insulating state persists even under extreme pressures, suggesting that a mechanism other than Mott is at work. Yet, given the complexity of the system, it is unclear to what extent the Mott picture can be really excluded. Here, we thus reexamine the problem. We show that, surprisingly, the pressure-induced enhancement of the screened Coulomb interaction—combined with lattice distortions and spin-orbit driven jeff=1/2 orbital ordering—can hold the system close to the metal-insulator transition up to very high pressure. Published by the American Physical Society2025
{"title":"Nature of the high-pressure insulating state in Sr2IrO4 : Mott picture","authors":"Guoren Zhang, Hanif Hadipour, Eva Pavarini","doi":"10.1103/physrevb.111.l121101","DOIUrl":"https://doi.org/10.1103/physrevb.111.l121101","url":null,"abstract":"At ambient pressure, the t</a:mi>2</a:mn>g</a:mi></a:mrow>5</a:mn></a:msubsup></a:math> layered perovskite <b:math xmlns:b=\"http://www.w3.org/1998/Math/MathML\"><b:msub><b:mrow><b:mi>Sr</b:mi></b:mrow><b:mn>2</b:mn></b:msub><b:msub><b:mrow><b:mi>IrO</b:mi></b:mrow><b:mn>4</b:mn></b:msub></b:math> is a correlated small-gap insulator. In the Mott picture, applying uniform pressure should therefore quickly close the gap; experimentally, however, the insulating state persists even under extreme pressures, suggesting that a mechanism other than Mott is at work. Yet, given the complexity of the system, it is unclear to what extent the Mott picture can be really excluded. Here, we thus reexamine the problem. We show that, surprisingly, the pressure-induced enhancement of the screened Coulomb interaction—combined with lattice distortions and spin-orbit driven <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\"><c:mrow><c:msub><c:mi>j</c:mi><c:mi>eff</c:mi></c:msub><c:mo>=</c:mo><c:mn>1</c:mn><c:mo>/</c:mo><c:mn>2</c:mn></c:mrow></c:math> orbital ordering—can hold the system close to the metal-insulator transition up to very high pressure. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"40 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143545947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-03DOI: 10.1103/physrevb.111.104402
Christopher Mudry, Ömer M. Aksoy, Claudio Chamon, Akira Furusaki
The anisotropic quantum spin-12 XY model on a linear chain was solved by Lieb, Schultz, and Mattis [] and shown to display a continuous quantum phase transition at the O(2) symmetric point separating two gapped phases with competing Ising long-range order. For the square lattice, the following is known. The two competing Ising ordered phases extend to finite temperatures, up to a boundary where a transition to the paramagnetic phase occurs, and meet at the O(2) symmetric critical line along the temperature axis that ends at a tricritical point at the Berezinskii-Kosterlitz-Thouless transition temperature where the two competing phases meet the paramagnetic phase. We show that the first-order zero-temperature (quantum) phase transition that separates the competing phases as a function of the anisotropy parameter is smoothed by thermal fluctuations into deconfined classical criticality. Published by the American Physical Society2025
{"title":"Deconfined classical criticality in the anisotropic quantum spin- 12 XY model on the square lattice","authors":"Christopher Mudry, Ömer M. Aksoy, Claudio Chamon, Akira Furusaki","doi":"10.1103/physrevb.111.104402","DOIUrl":"https://doi.org/10.1103/physrevb.111.104402","url":null,"abstract":"The anisotropic quantum spin-1</a:mn>2</a:mn></a:mfrac></a:math> XY model on a linear chain was solved by Lieb, Schultz, and Mattis [] and shown to display a continuous quantum phase transition at the O(2) symmetric point separating two gapped phases with competing Ising long-range order. For the square lattice, the following is known. The two competing Ising ordered phases extend to finite temperatures, up to a boundary where a transition to the paramagnetic phase occurs, and meet at the O(2) symmetric critical line along the temperature axis that ends at a tricritical point at the Berezinskii-Kosterlitz-Thouless transition temperature where the two competing phases meet the paramagnetic phase. We show that the first-order zero-temperature (quantum) phase transition that separates the competing phases as a function of the anisotropy parameter is smoothed by thermal fluctuations into deconfined classical criticality. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"34 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143538670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-28DOI: 10.1103/physrevb.111.054119
Juri Barthel, Leslie J. Allen
We generalize a recently proposed theory for atomic resolution phonon spectroscopy in scanning transmission electron microscopy, which explicitly includes the dependence of the spectrum on probe position, to apply to thick specimens, where probe channeling is important. We also take into account anisotropy due to atoms of the same species exhibiting different vibrational modes. This approach considers the contribution from individual atoms to the spectrum. Simulations to explore the dependence of the spectrum, in particular of its shape, on the probe position and thickness are carried out for the perovskite SrTiO3, which has recently been experimentally investigated, and computational efficiency is discussed. Published by the American Physical Society2025
{"title":"Practicable model for phonon spectroscopy at atomic resolution in scanning transmission electron microscopy for thick crystalline specimens","authors":"Juri Barthel, Leslie J. Allen","doi":"10.1103/physrevb.111.054119","DOIUrl":"https://doi.org/10.1103/physrevb.111.054119","url":null,"abstract":"We generalize a recently proposed theory for atomic resolution phonon spectroscopy in scanning transmission electron microscopy, which explicitly includes the dependence of the spectrum on probe position, to apply to thick specimens, where probe channeling is important. We also take into account anisotropy due to atoms of the same species exhibiting different vibrational modes. This approach considers the contribution from individual atoms to the spectrum. Simulations to explore the dependence of the spectrum, in particular of its shape, on the probe position and thickness are carried out for the perovskite SrTiO</a:mi>3</a:mn></a:msub></a:math>, which has recently been experimentally investigated, and computational efficiency is discussed. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"72 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1103/physrevb.111.054440
B. M. Huddart, A. Hernández-Melián, G. D. A. Wood, D. A. Mayoh, M. Gomilšek, Z. Guguchia, C. Wang, T. J. Hicken, S. J. Blundell, G. Balakrishnan, T. Lancaster
Centrosymmetric GdRu2Si2 exhibits a variety of multi-Q magnetic states as a function of temperature and applied magnetic field, including a square skyrmion-lattice phase. The material's behavior is strongly dependent on the direction of the applied field, with different phase diagrams resulting for fields applied parallel or perpendicular to the crystallographic c axis. Here, we present the results of muon-spin relaxation (μ+SR) measurements on single crystals of GdRu2Si2. Our analysis is based on the computation of muon stopping sites and consideration of quantum zero-point motion effects of muons, allowing direct comparison with the underlying spin textures in the material. The muon site is confirmed experimentally, using angle-dependent measurements of the muon Knight shift. Using transverse-field μ+SR with fields applied along either the [001] or [100] crystallographic directions, we distinguish between the magnetic phases in this system via their distinct muon response, providing additional evidence for the skyrmion and meron-lattice phases, while also suggesting the existence of RKKY-driven muon hyperfine coupling. Zero-field μ+SR provides clear evidence for a transition between two distinct magnetically ordered phases at 39 K. Published by the American Physical Society2025
{"title":"Field-orientation-dependent magnetic phases in GdRu2Si2 probed with muon-spin spectroscopy","authors":"B. M. Huddart, A. Hernández-Melián, G. D. A. Wood, D. A. Mayoh, M. Gomilšek, Z. Guguchia, C. Wang, T. J. Hicken, S. J. Blundell, G. Balakrishnan, T. Lancaster","doi":"10.1103/physrevb.111.054440","DOIUrl":"https://doi.org/10.1103/physrevb.111.054440","url":null,"abstract":"Centrosymmetric GdRu</a:mi>2</a:mn></a:msub>Si</a:mi>2</a:mn></a:msub></a:mrow></a:math> exhibits a variety of multi-<b:math xmlns:b=\"http://www.w3.org/1998/Math/MathML\"><b:mrow><b:mi>Q</b:mi></b:mrow></b:math> magnetic states as a function of temperature and applied magnetic field, including a square skyrmion-lattice phase. The material's behavior is strongly dependent on the direction of the applied field, with different phase diagrams resulting for fields applied parallel or perpendicular to the crystallographic <c:math xmlns:c=\"http://www.w3.org/1998/Math/MathML\"><c:mi>c</c:mi></c:math> axis. Here, we present the results of muon-spin relaxation (<d:math xmlns:d=\"http://www.w3.org/1998/Math/MathML\"><d:mrow><d:msup><d:mi>μ</d:mi><d:mo>+</d:mo></d:msup><d:mi>SR</d:mi></d:mrow></d:math>) measurements on single crystals of <e:math xmlns:e=\"http://www.w3.org/1998/Math/MathML\"><e:mrow><e:msub><e:mi>GdRu</e:mi><e:mn>2</e:mn></e:msub><e:msub><e:mi>Si</e:mi><e:mn>2</e:mn></e:msub></e:mrow></e:math>. Our analysis is based on the computation of muon stopping sites and consideration of quantum zero-point motion effects of muons, allowing direct comparison with the underlying spin textures in the material. The muon site is confirmed experimentally, using angle-dependent measurements of the muon Knight shift. Using transverse-field <f:math xmlns:f=\"http://www.w3.org/1998/Math/MathML\"><f:msup><f:mi>μ</f:mi><f:mo>+</f:mo></f:msup><f:mi>SR</f:mi></f:math> with fields applied along either the [001] or [100] crystallographic directions, we distinguish between the magnetic phases in this system via their distinct muon response, providing additional evidence for the skyrmion and meron-lattice phases, while also suggesting the existence of RKKY-driven muon hyperfine coupling. Zero-field <g:math xmlns:g=\"http://www.w3.org/1998/Math/MathML\"><g:mrow><g:msup><g:mi>μ</g:mi><g:mo>+</g:mo></g:msup><g:mi>SR</g:mi></g:mrow></g:math> provides clear evidence for a transition between two distinct magnetically ordered phases at 39 K. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"16 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143517939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1103/physrevb.111.085151
Marcel Gievers, Richard Schmidt, Jan von Delft, Fabian B. Kugler
The Fermi-edge singularity in x-ray absorption spectra of metals is a paradigmatic case of a logarithmically divergent perturbation series. Prior work has thoroughly analyzed the leading logarithmic terms. Here, we investigate the perturbation theory beyond leading logarithms and formulate self-consistent equations to incorporate all leading and next-to-leading logarithmic terms. This parquet solution of the Fermi-edge singularity goes beyond the previous first-order parquet solution and sheds new light on the parquet formalism regarding logarithmic behavior. We present numerical results in the Matsubara formalism and discuss the characteristic power laws. We also show that, within the single-boson exchange framework, multi-boson exchange diagrams are needed already at the leading logarithmic level. Published by the American Physical Society2025
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Pub Date : 2025-02-27DOI: 10.1103/physrevb.111.054117
Jing Yang, Ahmed Abdelkawy, Mira Todorova, Jörg Neugebauer
We propose an analytical thermodynamic model for describing defect phase transformations, which we term the statistical phase evaluation approach (SPEA). The SPEA model assumes a Boltzmann distribution of finite-size phase fractions and calculates their statistical average. To benchmark the performance of the model, we apply it to construct binary surface phase diagrams of metal alloys. Two alloy systems are considered: a Mg surface with Ca substitutions and a Ni surface with Nb substitutions. To construct a firm basis against which the performance of the analytical model can be leveled, we first perform Monte Carlo (MC) simulations coupled with cluster expansion of a density functional theory dataset. We then demonstrate that the SPEA model reproduces the MC results accurately. Specifically, it correctly predicts the surface order-disorder transitions as well as the coexistence of the 1/3 ordered phase and the disordered phase. Finally, we compare the SPEA method to the sublattice model commonly used in the CALPHAD approach to describe ordered and random solution phases and their transitions. The proposed SPEA model provides a highly efficient approach for modeling defect phase transformations. Published by the American Physical Society2025
{"title":"Statistical phase evaluation approach for defect phase diagrams","authors":"Jing Yang, Ahmed Abdelkawy, Mira Todorova, Jörg Neugebauer","doi":"10.1103/physrevb.111.054117","DOIUrl":"https://doi.org/10.1103/physrevb.111.054117","url":null,"abstract":"We propose an analytical thermodynamic model for describing defect phase transformations, which we term the statistical phase evaluation approach (SPEA). The SPEA model assumes a Boltzmann distribution of finite-size phase fractions and calculates their statistical average. To benchmark the performance of the model, we apply it to construct binary surface phase diagrams of metal alloys. Two alloy systems are considered: a Mg surface with Ca substitutions and a Ni surface with Nb substitutions. To construct a firm basis against which the performance of the analytical model can be leveled, we first perform Monte Carlo (MC) simulations coupled with cluster expansion of a density functional theory dataset. We then demonstrate that the SPEA model reproduces the MC results accurately. Specifically, it correctly predicts the surface order-disorder transitions as well as the coexistence of the 1/3 ordered phase and the disordered phase. Finally, we compare the SPEA method to the sublattice model commonly used in the CALPHAD approach to describe ordered and random solution phases and their transitions. The proposed SPEA model provides a highly efficient approach for modeling defect phase transformations. <jats:supplementary-material> <jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement> <jats:copyright-year>2025</jats:copyright-year> </jats:permissions> </jats:supplementary-material>","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":"85 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143517940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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