7 research outputs found
Superconductivity in model cuprate as an S=1 pseudomagnon condensation
We make use of the S=1 pseudospin formalism to describe the charge degree of
freedom in a model high- cuprate with the on-site Hilbert space reduced to
the three effective valence centers, nominally Cu. Starting
with a parent cuprate as an analogue of the quantum paramagnet ground state and
using the Schwinger boson technique we found the pseudospin spectrum and
conditions for the pseudomagnon condensation with phase transition to a
superconducting state.Comment: Version to be published in JLT
Unconventional phase transitions in strongly anisotropic 2D (pseudo)spin systems
We have applied a generalized mean-field approach and quantum Monte-Carlo technique for the model 2D S = 1 (pseudo)spin system to find the ground state phase with its evolution under application of the (pseudo)magnetic field. The comparison of the two methods allows us to clearly demonstrate the role of quantum effects. Special attention is given to the role played by an effective single-ion anisotropy (»on-site correlation»). © 2018 The Authors, published by EDP Sciences.The research was supported by the Government of the Russian Federation, Program 02.A03.21.0006 and by the Ministry of Education and Science of the Russian Federation, projects Nos. 2277 and 5719
Simple Realistic Model of Spin Reorientation in 4f-3d Compounds
This is a simple but realistic microscopic theory of spontaneous spin reorientation in rare-earth perovskites, orthoferrites RFeO3 and orthochromites RCrO3, induced by the 4f-3d interaction, namely, the interaction of the well-isolated ground-state Kramers doublet or non-Kramers quasi-doublet of the 4f ion with an effective magnetic field induced by 3d sublattice. Both the temperature and the nature of the spin-reorientation transition are the result of competition between the second-and fourth-order spin anisotropy of the 3d sublattice, the crystal field for 4f ions, and 4f-3d interaction. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 22-22-00682Funding: This research was funded by Russian Science Foundation grant number 22-22-00682
The MFA ground states for the extended Bose-Hubbard model with a three-body constraint
We address the intensively studied extended bosonic Hubbard model (EBHM) with
truncation of the on-site Hilbert space to the three lowest occupation states
n=0,1,2 in frames of the S=1 pseudospin formalism. Similar model was recently
proposed to describe the charge degree of freedom in a model high-Tc cuprate
with the on-site Hilbert space reduced to the three effective valence centers,
nominally Cu^{1+;2+;3+} . With small corrections the model becomes equivalent
to a strongly anisotropic S=1 quantum magnet in an external magnetic field. We
have applied a generalized mean-field approach and quantum Monte-Carlo
technique for the model 2D S=1 system with a two-particle transport to find the
ground state phase with its evolution under deviation from half-filling.Comment: 9 pages, 3 figure
Strongly Anisotropic S=1 (Pseudo) Spin Systems: from Mean Field to Quantum Monte-Carlo
Erratum to: Condensation of Pseudomagnons in a Two-Dimensional Anisotropic S = 1 Pseudospin System (Physics of the Solid State, (2018), 60, 11, (2145-2149), 10.1134/S1063783418110331)
E-mail address of the corresponding author should read: [email protected]. © 2019, Pleiades Publishing, Ltd
Strongly Anisotropic S=1 (Pseudo) Spin Systems: from Mean Field to Quantum Monte-Carlo
The S=1 pseudospin formalism was recently proposed to describe the charge degree of freedom in a model high-T_{c} cuprate with the on-site Hilbert space reduced to the three effective valence centers, nominally Cu^{1+;2+;3+}. With small corrections the model becomes equivalent to a strongly anisotropic S=1 quantum magnet in an external magnetic field. We have applied a generalized mean-field approach and quantum Monte-Carlo technique for the model 2D S=1 system to find the ground state phase with its evolution under deviation from half-filling and different correlation functions. Special attention is given to the role played by the on-site correlation ("single-ion anisotropy")