Effects of electron correlation, orbital degeneracy and Jahn-Teller coupling in perovskite manganites

Yukitoshi Motome, Masatoshi Imada

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Roles of Coulomb interaction, orbital degeneracy and Jahn-Teller coupling in double-exchange models are examined for perovskite Mn oxides. We study the undoped insulator as well as metal-insulator transitions by hole doping, and especially strong incoherence of ferromagnetic metal. We derive models where all the spins are fully polarized in two-dimensional planes as indicated by experimental results, and investigate their ground-state properties by the quantum Monte Carlo method. At half filling where the number of eg electrons is one per site on average, the Coulomb interaction opens a Mott gap and induces a staggered orbital ordering. The opening of the gap is, however, substantially slower than the mean-field results if the Jahn-Teller coupling is absent. The synergy between the strong correlation and the Jahn-Teller coupling largely enhances the charge gap amplitude and reproduces realistic amplitudes and stabilization energy of the Jahn-Teller distortion. Doping of carriers destroys the orbital ordering stabilized by the Coulomb interaction. The short-ranged orbital correlation is critically enhanced in metals toward the metal-insulator transition, which should be related to the strong incoherence of charge dynamics; observed in experiments. Our model, moreover, exhibits a uniform ordering of dx2-y2 orbitals over a wide region of doping in agreement with experimental indications.

Original languageEnglish
Pages (from-to)16-19
Number of pages4
JournalJournal of the Physical Society of Japan
Volume68
Issue number1
DOIs
Publication statusPublished - 1999 Jan 1
Externally publishedYes

Fingerprint

orbitals
incoherence
insulators
electrons
metals
interactions
Monte Carlo method
indication
stabilization
ground state
oxides
energy

Keywords

  • Coulomb interaction
  • Double-exchange model
  • Ferromagnetic metal
  • Incoherent charge dynamics
  • Jahn-Teller coupling
  • Jahn-Teller distortion
  • Metal-insulator transition
  • Mott gap
  • Orbital degeneracy
  • Orbital ordering
  • Perovskite manganites

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Effects of electron correlation, orbital degeneracy and Jahn-Teller coupling in perovskite manganites. / Motome, Yukitoshi; Imada, Masatoshi.

In: Journal of the Physical Society of Japan, Vol. 68, No. 1, 01.01.1999, p. 16-19.

Research output: Contribution to journalArticle

@article{58044ec29b4b439695008b3f14a3b5f8,
title = "Effects of electron correlation, orbital degeneracy and Jahn-Teller coupling in perovskite manganites",
abstract = "Roles of Coulomb interaction, orbital degeneracy and Jahn-Teller coupling in double-exchange models are examined for perovskite Mn oxides. We study the undoped insulator as well as metal-insulator transitions by hole doping, and especially strong incoherence of ferromagnetic metal. We derive models where all the spins are fully polarized in two-dimensional planes as indicated by experimental results, and investigate their ground-state properties by the quantum Monte Carlo method. At half filling where the number of eg electrons is one per site on average, the Coulomb interaction opens a Mott gap and induces a staggered orbital ordering. The opening of the gap is, however, substantially slower than the mean-field results if the Jahn-Teller coupling is absent. The synergy between the strong correlation and the Jahn-Teller coupling largely enhances the charge gap amplitude and reproduces realistic amplitudes and stabilization energy of the Jahn-Teller distortion. Doping of carriers destroys the orbital ordering stabilized by the Coulomb interaction. The short-ranged orbital correlation is critically enhanced in metals toward the metal-insulator transition, which should be related to the strong incoherence of charge dynamics; observed in experiments. Our model, moreover, exhibits a uniform ordering of dx2-y2 orbitals over a wide region of doping in agreement with experimental indications.",
keywords = "Coulomb interaction, Double-exchange model, Ferromagnetic metal, Incoherent charge dynamics, Jahn-Teller coupling, Jahn-Teller distortion, Metal-insulator transition, Mott gap, Orbital degeneracy, Orbital ordering, Perovskite manganites",
author = "Yukitoshi Motome and Masatoshi Imada",
year = "1999",
month = "1",
day = "1",
doi = "10.1143/JPSJ.68.16",
language = "English",
volume = "68",
pages = "16--19",
journal = "Journal of the Physical Society of Japan",
issn = "0031-9015",
publisher = "Physical Society of Japan",
number = "1",

}

TY - JOUR

T1 - Effects of electron correlation, orbital degeneracy and Jahn-Teller coupling in perovskite manganites

AU - Motome, Yukitoshi

AU - Imada, Masatoshi

PY - 1999/1/1

Y1 - 1999/1/1

N2 - Roles of Coulomb interaction, orbital degeneracy and Jahn-Teller coupling in double-exchange models are examined for perovskite Mn oxides. We study the undoped insulator as well as metal-insulator transitions by hole doping, and especially strong incoherence of ferromagnetic metal. We derive models where all the spins are fully polarized in two-dimensional planes as indicated by experimental results, and investigate their ground-state properties by the quantum Monte Carlo method. At half filling where the number of eg electrons is one per site on average, the Coulomb interaction opens a Mott gap and induces a staggered orbital ordering. The opening of the gap is, however, substantially slower than the mean-field results if the Jahn-Teller coupling is absent. The synergy between the strong correlation and the Jahn-Teller coupling largely enhances the charge gap amplitude and reproduces realistic amplitudes and stabilization energy of the Jahn-Teller distortion. Doping of carriers destroys the orbital ordering stabilized by the Coulomb interaction. The short-ranged orbital correlation is critically enhanced in metals toward the metal-insulator transition, which should be related to the strong incoherence of charge dynamics; observed in experiments. Our model, moreover, exhibits a uniform ordering of dx2-y2 orbitals over a wide region of doping in agreement with experimental indications.

AB - Roles of Coulomb interaction, orbital degeneracy and Jahn-Teller coupling in double-exchange models are examined for perovskite Mn oxides. We study the undoped insulator as well as metal-insulator transitions by hole doping, and especially strong incoherence of ferromagnetic metal. We derive models where all the spins are fully polarized in two-dimensional planes as indicated by experimental results, and investigate their ground-state properties by the quantum Monte Carlo method. At half filling where the number of eg electrons is one per site on average, the Coulomb interaction opens a Mott gap and induces a staggered orbital ordering. The opening of the gap is, however, substantially slower than the mean-field results if the Jahn-Teller coupling is absent. The synergy between the strong correlation and the Jahn-Teller coupling largely enhances the charge gap amplitude and reproduces realistic amplitudes and stabilization energy of the Jahn-Teller distortion. Doping of carriers destroys the orbital ordering stabilized by the Coulomb interaction. The short-ranged orbital correlation is critically enhanced in metals toward the metal-insulator transition, which should be related to the strong incoherence of charge dynamics; observed in experiments. Our model, moreover, exhibits a uniform ordering of dx2-y2 orbitals over a wide region of doping in agreement with experimental indications.

KW - Coulomb interaction

KW - Double-exchange model

KW - Ferromagnetic metal

KW - Incoherent charge dynamics

KW - Jahn-Teller coupling

KW - Jahn-Teller distortion

KW - Metal-insulator transition

KW - Mott gap

KW - Orbital degeneracy

KW - Orbital ordering

KW - Perovskite manganites

UR - http://www.scopus.com/inward/record.url?scp=0033472368&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033472368&partnerID=8YFLogxK

U2 - 10.1143/JPSJ.68.16

DO - 10.1143/JPSJ.68.16

M3 - Article

VL - 68

SP - 16

EP - 19

JO - Journal of the Physical Society of Japan

JF - Journal of the Physical Society of Japan

SN - 0031-9015

IS - 1

ER -