Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/111523
Title: Orbital Isotropy of Magnetic Fluctuations in Correlated Electron Materials Induced by Hund's Exchange Coupling
Authors: Stepanov, E. A.
Nomura, Y.
Lichtenstein, A. I.
Biermann, S.
Issue Date: 2021
Publisher: American Physical Society
American Physical Society (APS)
Citation: Orbital Isotropy of Magnetic Fluctuations in Correlated Electron Materials Induced by Hund's Exchange Coupling / E. A. Stepanov, Y. Nomura, A. I. Lichtenstein et al. // Physical Review Letters. — 2021. — Vol. 127. — Iss. 20. — 207205.
Abstract: Characterizing nonlocal magnetic fluctuations in materials with strong electronic Coulomb interactions remains one of the major outstanding challenges of modern condensed matter theory. In this Letter, we address the spatial symmetry and orbital structure of magnetic fluctuations in perovskite materials. To this aim, we develop a consistent multiorbital diagrammatic extension of dynamical mean-field theory, which we apply to an anisotropic three-orbital model of cubic t2g symmetry. We find that the form of spatial spin fluctuations is governed by the local Hund's coupling. For small values of the coupling, magnetic fluctuations are anisotropic in orbital space, which reflects the symmetry of the considered t2g model. Large Hund's coupling enhances collective spin excitations, which mixes orbital and spatial degrees of freedom, and magnetic fluctuations become orbitally isotropic. Remarkably, this effect can be seen only in two-particle quantities; single-particle observables remain anisotropic for any value of the Hund's coupling. Importantly, we find that the orbital isotropy can be induced both at half filling and for the case of four electrons per lattice site, where the magnetic instability is associated with different, antiferromagnetic and ferromagnetic, modes, respectively. © 2021 American Physical Society.
Keywords: DEGREES OF FREEDOM (MECHANICS)
MEAN FIELD THEORY
PEROVSKITE
SPIN FLUCTUATIONS
CONDENSED-MATTER THEORY
CORRELATED ELECTRON MATERIALS
DYNAMICAL MEAN-FIELD THEORY
ELECTRONIC COULOMB INTERACTIONS
HUND'S COUPLING
MAGNETIC FLUCTUATION
NONLOCAL
ORBITAL MODELS
ORBITALS
SPATIAL SYMMETRY
ANISOTROPY
ARTICLE
DEGREE OF FREEDOM
ELECTRON
EXCITATION
THEORETICAL STUDY
URI: http://hdl.handle.net/10995/111523
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85119173955
PURE ID: 28947798
ISSN: 0031-9007
metadata.dc.description.sponsorship: The authors thank Yvan Sidis, Eva Pavarini, Igor Mazin, and Josef Kaufmann for useful discussions and comments. The work of E. A. S. is supported by the Russian Science Foundation Grant No. 18-12-00185. The work of Y. N. is supported by JSPS KAKENHI 16H06345, 17K14336, 18H01158, and 20K14423. The work of A. I. L. is supported by European Research Council via Synergy Grant No. 854843—FASTCORR, by the Cluster of Excellence “Advanced Imaging of Matter” of the Deutsche Forschungsgemeinschaft (DFG)—EXC 2056—Project No. ID390715994, and by North-German Supercomputing Alliance (HLRN) under the Project No. hhp00042. S. B. acknowledges support from the French Agence Nationale de la Recherche in the framework of the collaborative DFG-ANR project RE-MAP (Project No. 316912154) and from IDRIS/GENCI Orsay under project t2020091393.
RSCF project card: 18-12-00185
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

Files in This Item:
File Description SizeFormat 
2-s2.0-85119173955.pdf1,16 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.