Pub Date : 2024-07-29DOI: 10.1103/physrevb.110.l041406
Cooper Finnigan, Dmitry K. Efimkin
Electron skew scattering by impurities is one of the major mechanisms behind the anomalous Hall effect in ferromagnetic nanostructures. It is particularly strong at the surface of topological insulators where electron dynamics is governed by the spin-1/2 Dirac equation. Motivated by recently discovered mappings between hydrodynamics and the spin-1 Dirac equation, we consider the scattering of plasma waves—propagating charge-density oscillations—excited in graphene off a nonuniform magnetic field created by an adjacent circular micromagnet. The calculated scattering amplitude not only exhibits a giant asymmetry, or skewness, but it is resonantly enhanced if the frequency of the incoming wave matches the frequency of the chiral trapped mode circulating the micromagnet in only one direction. Furthermore, if the frequency of the incoming plasma wave is a few times larger than the Larmor frequency, the angular distribution of its forward scattering is almost indistinguishable from that of a Dirac electron at the surface of a topological insulator scattering off a magnetic impurity. The micrometer scale of the proposed setup enables direct investigations of individual skew scattering events previously inaccessible in electronic systems.
{"title":"Giant resonant skew scattering of plasma waves in a two-dimensional electron gas","authors":"Cooper Finnigan, Dmitry K. Efimkin","doi":"10.1103/physrevb.110.l041406","DOIUrl":"https://doi.org/10.1103/physrevb.110.l041406","url":null,"abstract":"Electron skew scattering by impurities is one of the major mechanisms behind the anomalous Hall effect in ferromagnetic nanostructures. It is particularly strong at the surface of topological insulators where electron dynamics is governed by the spin-1/2 Dirac equation. Motivated by recently discovered mappings between hydrodynamics and the spin-1 Dirac equation, we consider the scattering of plasma waves—propagating charge-density oscillations—excited in graphene off a nonuniform magnetic field created by an adjacent circular micromagnet. The calculated scattering amplitude not only exhibits a giant asymmetry, or skewness, but it is resonantly enhanced if the frequency of the incoming wave matches the frequency of the chiral trapped mode circulating the micromagnet in only one direction. Furthermore, if the frequency of the incoming plasma wave is a few times larger than the Larmor frequency, the angular distribution of its forward scattering is almost indistinguishable from that of a Dirac electron at the surface of a topological insulator scattering off a magnetic impurity. The micrometer scale of the proposed setup enables direct investigations of individual skew scattering events previously inaccessible in electronic systems.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791064","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 : 2024-07-29DOI: 10.1103/physrevb.110.014209
Marlena Dziurawiec, Jessica O. de Almeida, Mohit Lal Bera, Marcin Płodzień, Maciej M. Maśka, Maciej Lewenstein, Tobias Grass, Utso Bhattacharya
We show that high-harmonic spectroscopy offers an advanced avenue for probing electronic properties of quasicrystals beyond the linear response regime. Focusing on Aubry-André-Harper (AAH) chains, we extract the multifractal spectrum from the harmonic emission intensity—an essential indicator of the spatial distribution of electronic states in quasicrystals. Additionally, we address the detection of mobility edges, vital energy thresholds that demarcate localized and extended eigenstates within generalized AAH models. The precise identification of these mobility edges sheds light on the metal-insulator transition and the behavior of electronic states near these boundaries. Merging high-harmonic spectroscopy with the AAH model provides a powerful framework for understanding the interplay between localization and extended states in quasicrystals for an extremely wide energy range not captured within linear response studies, thereby offering valuable insights for guiding future experimental investigations.
{"title":"Unraveling multifractality and mobility edges in quasiperiodic Aubry-André-Harper chains through high-harmonic generation","authors":"Marlena Dziurawiec, Jessica O. de Almeida, Mohit Lal Bera, Marcin Płodzień, Maciej M. Maśka, Maciej Lewenstein, Tobias Grass, Utso Bhattacharya","doi":"10.1103/physrevb.110.014209","DOIUrl":"https://doi.org/10.1103/physrevb.110.014209","url":null,"abstract":"We show that high-harmonic spectroscopy offers an advanced avenue for probing electronic properties of quasicrystals beyond the linear response regime. Focusing on Aubry-André-Harper (AAH) chains, we extract the multifractal spectrum from the harmonic emission intensity—an essential indicator of the spatial distribution of electronic states in quasicrystals. Additionally, we address the detection of mobility edges, vital energy thresholds that demarcate localized and extended eigenstates within generalized AAH models. The precise identification of these mobility edges sheds light on the metal-insulator transition and the behavior of electronic states near these boundaries. Merging high-harmonic spectroscopy with the AAH model provides a powerful framework for understanding the interplay between localization and extended states in quasicrystals for an extremely wide energy range not captured within linear response studies, thereby offering valuable insights for guiding future experimental investigations.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791046","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 : 2024-07-29DOI: 10.1103/physrevb.110.014442
Yunxi Qi, Jun Zhao, Hui Zeng
Recently, the discovery of collinear symmetric-compensated antiferromagnets (AFMs) with intrinsic spin splitting has attracted enormous interest of many researchers. In this paper, we predict the spin-layer coupling in altermagnetic bilayers with tunable spin and valley splitting properties via first-principles calculations. Based on the analysis of magnetic symmetry, we find manipulating magnetic order and stacking configuration as a strategy. Compared with conventional AFM bilayers, the joint symmetry in altermagnetic bilayer can be significantly modulated by different magnetic orders and stackings of the two sublayers. Furthermore, we demonstrate that the layer-dependent spin degeneracy/splitting widely exists in altermagnets with different crystal structures. The spin splitting in an altermagnetic bilayer with various interlayer couplings is highly tunable by external electric field. In contrast with spin splitting introduced by conventional spin-orbit coupling, the concepts of emerging layertronics and altermagnets are combined to manipulate spin properties by spin-layer coupling, ensuring both long spin relaxation time and complete spin splitting for practical applications of spintronic devices.
{"title":"Spin-layer coupling in two-dimensional altermagnetic bilayers with tunable spin and valley splitting properties","authors":"Yunxi Qi, Jun Zhao, Hui Zeng","doi":"10.1103/physrevb.110.014442","DOIUrl":"https://doi.org/10.1103/physrevb.110.014442","url":null,"abstract":"Recently, the discovery of collinear symmetric-compensated antiferromagnets (AFMs) with intrinsic spin splitting has attracted enormous interest of many researchers. In this paper, we predict the spin-layer coupling in altermagnetic bilayers with tunable spin and valley splitting properties via first-principles calculations. Based on the analysis of magnetic symmetry, we find manipulating magnetic order and stacking configuration as a strategy. Compared with conventional AFM bilayers, the joint symmetry in altermagnetic bilayer can be significantly modulated by different magnetic orders and stackings of the two sublayers. Furthermore, we demonstrate that the layer-dependent spin degeneracy/splitting widely exists in altermagnets with different crystal structures. The spin splitting in an altermagnetic bilayer with various interlayer couplings is highly tunable by external electric field. In contrast with spin splitting introduced by conventional spin-orbit coupling, the concepts of emerging layertronics and altermagnets are combined to manipulate spin properties by spin-layer coupling, ensuring both long spin relaxation time and complete spin splitting for practical applications of spintronic devices.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791048","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 : 2024-07-26DOI: 10.1103/physrevb.110.024431
Mori Watanabe, Tomo Higashihara, Ryotaro Asama, Masashi Tokuda, Shota Suzuki, Nan Jiang, Masayuki Ochi, Hiroaki Ishizuka, Hiroyuki K. Yoshida, Yasuhiro Niimi
We studied the electrical transport properties of a classical spin triangular lattice antiferromagnet . In this material, a unique spin structure with a five-sublattice unit cell emerges below the Néel temperature , owing to frustration from strong further-neighbor interactions. The material also exhibits unique electrical transport properties coupled with its magnetism, due to a highly conductive layer of . Here, we report magnetoresistance and the Hall effect in flake devices below and above up to a magnetic field of 8 T. A large magnetoresistance and anomalous Hall effect were observed in the vicinity of , indicating that the fluctuation of the magnetic moments plays a key role. We propose possible scenarios in which the anomalous Hall effect is enhanced through thermal fluctuation.
{"title":"Unconventional anomalous Hall effect in a triangular lattice antiferromagnet","authors":"Mori Watanabe, Tomo Higashihara, Ryotaro Asama, Masashi Tokuda, Shota Suzuki, Nan Jiang, Masayuki Ochi, Hiroaki Ishizuka, Hiroyuki K. Yoshida, Yasuhiro Niimi","doi":"10.1103/physrevb.110.024431","DOIUrl":"https://doi.org/10.1103/physrevb.110.024431","url":null,"abstract":"We studied the electrical transport properties of a classical spin triangular lattice antiferromagnet <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Ag</mi><mn>2</mn></msub><msub><mi>CrO</mi><mn>2</mn></msub></mrow></math>. In this material, a unique spin structure with a five-sublattice unit cell emerges below the Néel temperature <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi mathvariant=\"normal\">N</mi></msub></math>, owing to frustration from strong further-neighbor interactions. The material also exhibits unique electrical transport properties coupled with its magnetism, due to a highly conductive layer of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>Ag</mi><mn>2</mn></msub></math>. Here, we report magnetoresistance and the Hall effect in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>Ag</mi><mn>2</mn></msub><msub><mi>CrO</mi><mn>2</mn></msub></mrow></math> flake devices below and above <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi mathvariant=\"normal\">N</mi></msub></math> up to a magnetic field of 8 T. A large magnetoresistance and anomalous Hall effect were observed in the vicinity of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi mathvariant=\"normal\">N</mi></msub></math>, indicating that the fluctuation of the magnetic moments plays a key role. We propose possible scenarios in which the anomalous Hall effect is enhanced through thermal fluctuation.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764262","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}
We investigate the magneto-optical properties of two-dimensional nonsymmorphic Dirac semimetals in the presence of antiferromagnetic order. Using the Kubo formula, we calculate the conductivity tensor of two-dimensional CuMnAs, a prototype antiferromagnetic Dirac material, as a function of light frequency. From the finite-frequency conductivity tensor, we derive the dynamic dielectric function and magnetic linear dichroism, demonstrating how they are influenced by the orientation of the Néel order parameter. Adjusting the Néel vector changes both the sign and amplitude of the system's magneto-optical response. We propose that magnetic linear dichroism spectroscopy is a powerful technique for determining the orientation of the Néel vector.
{"title":"AC conductivity and magnetic dichroism of two-dimensional antiferromagnetic Dirac semimetals","authors":"Reza Sepehrinia, Siavash Eskandari, Alireza Qaiumzadeh","doi":"10.1103/physrevb.110.014440","DOIUrl":"https://doi.org/10.1103/physrevb.110.014440","url":null,"abstract":"We investigate the magneto-optical properties of two-dimensional nonsymmorphic Dirac semimetals in the presence of antiferromagnetic order. Using the Kubo formula, we calculate the conductivity tensor of two-dimensional CuMnAs, a prototype antiferromagnetic Dirac material, as a function of light frequency. From the finite-frequency conductivity tensor, we derive the dynamic dielectric function and magnetic linear dichroism, demonstrating how they are influenced by the orientation of the Néel order parameter. Adjusting the Néel vector changes both the sign and amplitude of the system's magneto-optical response. We propose that magnetic linear dichroism spectroscopy is a powerful technique for determining the orientation of the Néel vector.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764275","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 : 2024-07-26DOI: 10.1103/physrevb.110.035158
Jun Mochida, Yuto Ashida
In metals containing magnetic impurities, conduction electrons screen the magnetic impurities and induce the Kondo effect, i.e., the enhancement of the electrical resistance at low temperatures. Motivated by recent advances in manipulating quantum materials by cavity confinement, we study how the ultrastrong light-matter coupling can affect the Kondo effect. We show that the ultrastrong coupling can enhance the Kondo temperature and give rise to several notable phenomena, including universal scalings of the cavity-modified Kondo effect, the photon occupation number, and the entanglement entropy between the cavity and electrons. The origin of the cavity enhancement can be understood from the mass renormalization due to the cavity-mediated nonlocal electron-electron interaction, which is akin to the polaronic mass enhancement. We combine the unitary transformations and the Gaussian variational states to analyze the quantum impurity system confined in the cavity. Our nonperturbative framework can be applied to a variety of quantum impurity problems influenced by structured quantum electromagnetic environment.
{"title":"Cavity-enhanced Kondo effect","authors":"Jun Mochida, Yuto Ashida","doi":"10.1103/physrevb.110.035158","DOIUrl":"https://doi.org/10.1103/physrevb.110.035158","url":null,"abstract":"In metals containing magnetic impurities, conduction electrons screen the magnetic impurities and induce the Kondo effect, i.e., the enhancement of the electrical resistance at low temperatures. Motivated by recent advances in manipulating quantum materials by cavity confinement, we study how the ultrastrong light-matter coupling can affect the Kondo effect. We show that the ultrastrong coupling can enhance the Kondo temperature and give rise to several notable phenomena, including universal scalings of the cavity-modified Kondo effect, the photon occupation number, and the entanglement entropy between the cavity and electrons. The origin of the cavity enhancement can be understood from the mass renormalization due to the cavity-mediated nonlocal electron-electron interaction, which is akin to the polaronic mass enhancement. We combine the unitary transformations and the Gaussian variational states to analyze the quantum impurity system confined in the cavity. Our nonperturbative framework can be applied to a variety of quantum impurity problems influenced by structured quantum electromagnetic environment.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764269","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 : 2024-07-26DOI: 10.1103/physrevb.110.045147
Khachatur G. Nazaryan, Leonid Levitov
Vortices in electron fluids are a key indicator of electron hydrodynamics. However, a comprehensive framework linking macroscopic vorticity measurements with microscopic interactions and scattering mechanisms has been lacking. We employ wave-number-dependent conductivity , which incorporates rates of realistic microscopic scattering processes and is built as a continued fraction from decay rates for different excitations. This approach is used to clarify the relationship between nonlocal response and vortices across ballistic and hydrodynamic phases. Vorticity exhibits similar values in both phases but shows markedly different sensitivity to momentum-relaxing scattering, with ballistic vortical flows being orders-of-magnitude more resilient than the hydrodynamic ones. This behavior can serve as a diagnostic of the microscopic origin of vorticity in electron fluids.
{"title":"Nonlocal conductivity, continued fractions, and current vortices in electron fluids","authors":"Khachatur G. Nazaryan, Leonid Levitov","doi":"10.1103/physrevb.110.045147","DOIUrl":"https://doi.org/10.1103/physrevb.110.045147","url":null,"abstract":"Vortices in electron fluids are a key indicator of electron hydrodynamics. However, a comprehensive framework linking macroscopic vorticity measurements with microscopic interactions and scattering mechanisms has been lacking. We employ wave-number-dependent conductivity <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>σ</mi><mo>(</mo><mi>k</mi><mo>)</mo></mrow></math>, which incorporates rates of realistic microscopic scattering processes and is built as a continued fraction from decay rates for different excitations. This approach is used to clarify the relationship between nonlocal response and vortices across ballistic and hydrodynamic phases. Vorticity exhibits similar values in both phases but shows markedly different sensitivity to momentum-relaxing scattering, with ballistic vortical flows being orders-of-magnitude more resilient than the hydrodynamic ones. This behavior can serve as a diagnostic of the microscopic origin of vorticity in electron fluids.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764273","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 : 2024-07-26DOI: 10.1103/physrevb.110.l020103
T. Hara, N. Katayama, S. Kitou, K. Kojima, S. Kawaguchi, H. Sawa
We present a high-pressure single-crystal x-ray structure analysis of two-dimensional layered , which is known to undergo an incommensurate charge density wave transition at 110 K at ambient pressure. When pressure is applied to at 150 K, a structural phase transition appears at about 8 GPa. The structural analysis of x-ray diffraction data obtained from a single crystal sample, with the correct corrections for the use of a diamond anvil cell and taking into account the effects of multiple domains, using only the superlattice peaks, reveals the appearance of “ribbon chain” type vanadium clusters at a high-pressure region. The formation of Se-Se bonds under high pressure and the associated unexpected charge injection into vanadium are largely responsible for the formation of ribbon-chain clusters. We discuss the possibility that such interanion bond formation occurs universally in the high-pressure phase of transition metal diserenides.
我们对二维层状 1T-VSe2 进行了高压单晶 X 射线结构分析，已知其在 110 K 的环境压力下会发生不相称的电荷密度波转变。当在 150 K 时对 1T-VSe2 施压，在约 8 GPa 时会出现结构相变。对从单晶体样品中获得的 X 射线衍射数据进行结构分析后发现，在高压区域出现了 "带状链 "型钒簇。高压下 Se-Se 键的形成以及相关的意外电荷注入钒在很大程度上导致了带状链团簇的形成。我们讨论了这种阴离子间键的形成普遍发生在过渡金属二硒化物高压相中的可能性。
{"title":"Pseudo-one-dimensional ribbon chain cluster realized under high pressure in 1T−VSe2","authors":"T. Hara, N. Katayama, S. Kitou, K. Kojima, S. Kawaguchi, H. Sawa","doi":"10.1103/physrevb.110.l020103","DOIUrl":"https://doi.org/10.1103/physrevb.110.l020103","url":null,"abstract":"We present a high-pressure single-crystal x-ray structure analysis of two-dimensional layered <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mi>T</mi></mrow><mtext>−</mtext><msub><mi>VSe</mi><mn>2</mn></msub></math>, which is known to undergo an incommensurate charge density wave transition at 110 K at ambient pressure. When pressure is applied to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mi>T</mi></mrow><mtext>−</mtext><msub><mi>VSe</mi><mn>2</mn></msub></math> at 150 K, a structural phase transition appears at about 8 GPa. The structural analysis of x-ray diffraction data obtained from a single crystal sample, with the correct corrections for the use of a diamond anvil cell and taking into account the effects of multiple domains, using only the superlattice peaks, reveals the appearance of “ribbon chain” type vanadium clusters at a high-pressure region. The formation of Se-Se bonds under high pressure and the associated unexpected charge injection into vanadium are largely responsible for the formation of ribbon-chain clusters. We discuss the possibility that such interanion bond formation occurs universally in the high-pressure phase of transition metal diserenides.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768454","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 : 2024-07-26DOI: 10.1103/physrevb.110.014439
Nao Furukawa, Qing-Ping Ding, Juan Schmidt, Sergey L. Bud'ko, Paul C. Canfield, Yuji Furukawa
with a tetragonal structure is known to be a Stoner-enhanced Pauli paramagnetic metal being nearly ferromagnetic. Recently J. Schmidt et al. [Phys. Rev. B108, 174415 (2023)] reported that a ferromagnetic ordered state is actually induced by a small Ni substitution for Co of in where an antiferromagnetic ordered phase also appears by further Ni substitution with . Here, using nuclear magnetic resonance (NMR) measurements on nuclei, we have investigated how the magnetic properties change by the Ni substitution in from a microscopic point of view, especially focusing on the evolution of magnetic fluctuations with the Ni substitution and the characterization of the magnetically ordered states. The temperature dependencies of the spin-lattice relaxation rate divided by temperature and Knight shift for are reasonably explained by a model where a double-peak structure for the density of states near the Fermi energy is assumed. Based on a Korringa ratio analysis using the and data, ferromagnetic spin fluctuations are found to dominate in the ferromagnetic
{"title":"Inhomogeneous magnetic ordered state and evolution of magnetic fluctuations in Sr(Co1−xNix)2P2 revealed by P31 NMR","authors":"Nao Furukawa, Qing-Ping Ding, Juan Schmidt, Sergey L. Bud'ko, Paul C. Canfield, Yuji Furukawa","doi":"10.1103/physrevb.110.014439","DOIUrl":"https://doi.org/10.1103/physrevb.110.014439","url":null,"abstract":"<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>SrCo</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">P</mi><mn>2</mn></msub></mrow></math> with a tetragonal structure is known to be a Stoner-enhanced Pauli paramagnetic metal being nearly ferromagnetic. Recently J. Schmidt <i>et al.</i> [<span>Phys. Rev. B</span> <b>108</b>, 174415 (2023)] reported that a ferromagnetic ordered state is actually induced by a small Ni substitution for Co of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>0.02</mn></mrow></math> in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Sr</mi><msub><mrow><mo>(</mo><msub><mi>Co</mi><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><msub><mi>Ni</mi><mi>x</mi></msub><mo>)</mo></mrow><mn>2</mn></msub><msub><mi mathvariant=\"normal\">P</mi><mn>2</mn></msub></mrow></math> where an antiferromagnetic ordered phase also appears by further Ni substitution with <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>0.06</mn><mo>–</mo><mn>0.35</mn></mrow></math>. Here, using nuclear magnetic resonance (NMR) measurements on <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mmultiscripts><mi mathvariant=\"normal\">P</mi><mprescripts></mprescripts><none></none><mn>31</mn></mmultiscripts></math> nuclei, we have investigated how the magnetic properties change by the Ni substitution in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Sr</mi><msub><mrow><mo>(</mo><msub><mi>Co</mi><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><msub><mi>Ni</mi><mi>x</mi></msub><mo>)</mo></mrow><mn>2</mn></msub><msub><mi mathvariant=\"normal\">P</mi><mn>2</mn></msub></mrow></math> from a microscopic point of view, especially focusing on the evolution of magnetic fluctuations with the Ni substitution and the characterization of the magnetically ordered states. The temperature dependencies of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mmultiscripts><mi mathvariant=\"normal\">P</mi><mprescripts></mprescripts><none></none><mn>31</mn></mmultiscripts></math> spin-lattice relaxation rate divided by temperature <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>(</mo><mn>1</mn><mo>/</mo><msub><mi>T</mi><mn>1</mn></msub><mi>T</mi><mo>)</mo></mrow></math> and Knight shift <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>(</mo><mi>K</mi><mo>)</mo></math> for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>SrCo</mi><mn>2</mn></msub><msub><mi mathvariant=\"normal\">P</mi><mn>2</mn></msub></mrow></math> are reasonably explained by a model where a double-peak structure for the density of states near the Fermi energy is assumed. Based on a Korringa ratio analysis using the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mn>1</mn></msub></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>K</mi></math> data, ferromagnetic spin fluctuations are found to dominate in the ferromagnetic <math xmlns=\"http://www.w3.org/1998/Mat","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764261","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 : 2024-07-26DOI: 10.1103/physrevb.110.014438
Sevda Sahinbay, Hong Zheng, J. F. Mitchell, Stephan Rosenkranz, Omar Chmaissem
The system is a prototype geometrically frustrated magnet in which kagome planes and triangular layers of Co-O tetrahedra interleave. For , an antiferromagnetic ground state is realized due to a frustration-breaking trigonal-orthorhombic phase transition. For , however, a long-range ordered state has rarely, if ever, been reported despite a similar symmetry-breaking transition, albeit at a significantly lower temperature. To explore this dichotomy, we present a comprehensive magnetic and structural phase diagram for , established through complementary neutron diffraction and magnetization measurements. Our results outline the phase evolution of the nuclear structures in response to changes in composition and temperature. The temperature of the trigonal () to orthorhombic () transition, , decreases monotonically with increasing Lu content from 310 K for to 110 K for . In Lu-rich compositions (), first-order structural transitions are observed with coexisting and competing orthorhombic and metastable monoclinic phases. For the magnetically ordered Y-rich compositions, - and -dependent refinements of the magnetic structure reveal an
RBaCo4O7 系统是一种几何挫折磁体的原型，其中的卡戈米平面和 Co-O 四面体的三角形层相互交错。当 R=Y 时，由于沮度打破了三方-正方相变，因此实现了反铁磁基态。然而，对于 R=Lu，尽管存在类似的对称性破坏转变，但却很少有长程有序态的报道，尽管其温度要低得多。为了探索这种二分法，我们通过互补的中子衍射和磁化测量，绘制了 Y1-xLuxBaCo4O7 的综合磁性和结构相图。我们的研究结果概述了核结构随成分和温度变化而发生的相变。三方（P31c）到正方（Pbn21）转变的温度 Ts1 随 Lu 含量的增加而单调降低，从 x=0.0 时的 310 K 到 x=1.0 时的 110 K。在富含 Lu 的成分（0.7≤x≤1.0）中，可以观察到一阶结构转变，即正交 Pbn21 相和蜕变单斜 Cc 相共存和竞争。对于磁性有序的富 Y 成分，磁性结构的 T 和 x 依赖性细化揭示了 Co 自旋对在三角形和卡戈米层中的反铁磁性 "带状 "排列。随着 Lu 含量的增加，长程磁有序性逐渐减弱，同时所有样品中都出现了短程磁相关性。
{"title":"Frustration-mediated crossover from long-range to short-range magnetic ordering in Y1–xLuxBaCo4O7","authors":"Sevda Sahinbay, Hong Zheng, J. F. Mitchell, Stephan Rosenkranz, Omar Chmaissem","doi":"10.1103/physrevb.110.014438","DOIUrl":"https://doi.org/10.1103/physrevb.110.014438","url":null,"abstract":"The <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>R</mi><mi>BaC</mi><msub><mi mathvariant=\"normal\">o</mi><mn>4</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>7</mn></msub></mrow></math> system is a prototype geometrically frustrated magnet in which kagome planes and triangular layers of Co-O tetrahedra interleave. For <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>R</mi><mo>=</mo><mi mathvariant=\"normal\">Y</mi></mrow></math>, an antiferromagnetic ground state is realized due to a frustration-breaking trigonal-orthorhombic phase transition. For <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>R</mi><mo>=</mo><mi>Lu</mi></mrow></math>, however, a long-range ordered state has rarely, if ever, been reported despite a similar symmetry-breaking transition, albeit at a significantly lower temperature. To explore this dichotomy, we present a comprehensive magnetic and structural phase diagram for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi mathvariant=\"normal\">Y</mi><mrow><mn>1</mn><mo>–</mo><mi>x</mi></mrow></msub><mi mathvariant=\"normal\">L</mi><msub><mi mathvariant=\"normal\">u</mi><mi>x</mi></msub><mi>BaC</mi><msub><mi mathvariant=\"normal\">o</mi><mn>4</mn></msub><msub><mi mathvariant=\"normal\">O</mi><mn>7</mn></msub></mrow></math>, established through complementary neutron diffraction and magnetization measurements. Our results outline the phase evolution of the nuclear structures in response to changes in composition and temperature. The temperature of the trigonal (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>P</mi><mn>31</mn><mi>c</mi></mrow></math>) to orthorhombic (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>P</mi><mi>b</mi><mi>n</mi><msub><mn>2</mn><mn>1</mn></msub></mrow></math>) transition, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mrow><mi mathvariant=\"normal\">s</mi><mn>1</mn></mrow></msub></math>, decreases monotonically with increasing Lu content from 310 K for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>0.0</mn></mrow></math> to 110 K for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>x</mi><mo>=</mo><mn>1.0</mn></mrow></math>. In Lu-rich compositions (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>0.7</mn><mo>≤</mo><mi>x</mi><mo>≤</mo><mn>1.0</mn></mrow></math>), first-order structural transitions are observed with coexisting and competing orthorhombic <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>P</mi><mi>b</mi><mi>n</mi><msub><mn>2</mn><mn>1</mn></msub></mrow></math> and metastable monoclinic <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"italic\">Cc</mi></mrow></math> phases. For the magnetically ordered Y-rich compositions, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>T</mi></mrow></math>- and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>x</mi></math>-dependent refinements of the magnetic structure reveal an ","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764296","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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