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Title: Fragility of the A-Type AF and CE Phases of Manganites: Insulator-To-Metal Transition Induced by Quenched Disorder

Abstract

Using Monte Carlo simulations and the two eg-orbital model for manganites, the stability of the CE and A-type antiferromagnetic insulating states is analyzed when quenched disorder in the superexchange JAF between the t2g localized spins and in the on-site energies is introduced. At vanishing or small values of the electron-Jahn-Teller phonon coupling, the previously hinted "fragility" of these insulating states is studied in detail, focusing on their charge transport properties. This fragility is here found to induce a rapid transition from the insulator to a poor metallic state upon the introduction of disorder. A possible qualitative explanation is presented based on the close proximity in energy of ferromagnetic metallic phases, and also on percolative ideas valid at large disorder strength. The scenario is compared with previously discussed insulator-to-metal transitions in other contexts. This particularly severe effect of disorder must be present in other materials as well, in cases involving phases that arise as a compromise between very different tendencies, as it probably occurs with striped states in the cuprates.

Authors:
 [1];  [1];  [2];  [1]
  1. ORNL
  2. Florida State University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
OSTI Identifier:
930842
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 73
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHARGE TRANSPORT; CUPRATES; FOCUSING; PHONONS; STABILITY; AF; CE Fragility

Citation Formats

Alvarez, Gonzalo, Aliaga, Horacio A, Sen, Cengiz, and Dagotto, Elbio R. Fragility of the A-Type AF and CE Phases of Manganites: Insulator-To-Metal Transition Induced by Quenched Disorder. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.73.224426.
Alvarez, Gonzalo, Aliaga, Horacio A, Sen, Cengiz, & Dagotto, Elbio R. Fragility of the A-Type AF and CE Phases of Manganites: Insulator-To-Metal Transition Induced by Quenched Disorder. United States. doi:10.1103/PhysRevB.73.224426.
Alvarez, Gonzalo, Aliaga, Horacio A, Sen, Cengiz, and Dagotto, Elbio R. Sun . "Fragility of the A-Type AF and CE Phases of Manganites: Insulator-To-Metal Transition Induced by Quenched Disorder". United States. doi:10.1103/PhysRevB.73.224426.
@article{osti_930842,
title = {Fragility of the A-Type AF and CE Phases of Manganites: Insulator-To-Metal Transition Induced by Quenched Disorder},
author = {Alvarez, Gonzalo and Aliaga, Horacio A and Sen, Cengiz and Dagotto, Elbio R},
abstractNote = {Using Monte Carlo simulations and the two eg-orbital model for manganites, the stability of the CE and A-type antiferromagnetic insulating states is analyzed when quenched disorder in the superexchange JAF between the t2g localized spins and in the on-site energies is introduced. At vanishing or small values of the electron-Jahn-Teller phonon coupling, the previously hinted "fragility" of these insulating states is studied in detail, focusing on their charge transport properties. This fragility is here found to induce a rapid transition from the insulator to a poor metallic state upon the introduction of disorder. A possible qualitative explanation is presented based on the close proximity in energy of ferromagnetic metallic phases, and also on percolative ideas valid at large disorder strength. The scenario is compared with previously discussed insulator-to-metal transitions in other contexts. This particularly severe effect of disorder must be present in other materials as well, in cases involving phases that arise as a compromise between very different tendencies, as it probably occurs with striped states in the cuprates.},
doi = {10.1103/PhysRevB.73.224426},
journal = {Physical Review B},
number = ,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}