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Title: One- and Two-Band Models for Colossal Magnetoresistive Manganites Studied Using the Truncated Polynomial Expansion Method

Abstract

Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance

Authors:
 [1];  [2];  [3];  [4];  [2];  [2];  [2];  [2]
  1. Florida State University
  2. ORNL
  3. RIKEN, Japan
  4. Aoyama Gakuin University, Kanagawa, Japan
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1003612
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 73; Journal Issue: 22
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; MAGNETORESISTANCE; POLYNOMIALS; PHYSICS; magnetoresistive; manganites; truncated polynomial

Citation Formats

Sen, Cengiz, Alvarez, Gonzalo, Motome, Y., Furukawa, N., Sergienko, Ivan A, Schulthess, Thomas C, Moreo, Adriana, and Dagotto, Elbio R. One- and Two-Band Models for Colossal Magnetoresistive Manganites Studied Using the Truncated Polynomial Expansion Method. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.73.224430.
Sen, Cengiz, Alvarez, Gonzalo, Motome, Y., Furukawa, N., Sergienko, Ivan A, Schulthess, Thomas C, Moreo, Adriana, & Dagotto, Elbio R. One- and Two-Band Models for Colossal Magnetoresistive Manganites Studied Using the Truncated Polynomial Expansion Method. United States. doi:10.1103/PhysRevB.73.224430.
Sen, Cengiz, Alvarez, Gonzalo, Motome, Y., Furukawa, N., Sergienko, Ivan A, Schulthess, Thomas C, Moreo, Adriana, and Dagotto, Elbio R. Sun . "One- and Two-Band Models for Colossal Magnetoresistive Manganites Studied Using the Truncated Polynomial Expansion Method". United States. doi:10.1103/PhysRevB.73.224430.
@article{osti_1003612,
title = {One- and Two-Band Models for Colossal Magnetoresistive Manganites Studied Using the Truncated Polynomial Expansion Method},
author = {Sen, Cengiz and Alvarez, Gonzalo and Motome, Y. and Furukawa, N. and Sergienko, Ivan A and Schulthess, Thomas C and Moreo, Adriana and Dagotto, Elbio R},
abstractNote = {Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance},
doi = {10.1103/PhysRevB.73.224430},
journal = {Physical Review B},
number = 22,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Considerable progress has been recently made in the theoretical understanding of the colossal magnetoresistance (CMR) effect in manganites. The existence of inhomogeneous states has been shown to be directly related with this phenomenon, both in theoretical studies and experimental investigations. The analysis of simple models with two competing states and a resistor network approximation to calculate conductances has confirmed that CMR effects can be theoretically reproduced using nonuniform clustered states. However, a direct computational study of the CMR effect in realistic models has been difficult since large clusters are needed for this purpose. In this paper, the recently proposed truncatedmore » polynomial expansion method (TPEM) for spin-fermion systems is tested using the double-exchange one-orbital, with finite Hund coupling J{sub H}, and two-orbital, with infinite J{sub H}, models. Two dimensional lattices as large as 48 x 48 are studied, far larger than those that can be handled with standard exact diagonalization (DIAG) techniques for the fermionic sector. The clean limit (i.e., without quenched disorder) is analyzed here in detail. Phase diagrams are obtained, showing first-order transitions separating ferromagnetic metallic from insulating states. A huge magnetoresistance is found at low temperatures by including small magnetic fields, in excellent agreement with experiments. However, at temperatures above the Curie transition the effect is much smaller confirming that the standard finite-temperature CMR phenomenon cannot be understood using homogeneous states. By comparing results between the two methods, TPEM and DIAG, on small lattices, and by analyzing the systematic behavior with increasing cluster sizes, it is concluded that the TPEM is accurate enough to handle realistic manganite models on large systems. Our results contribute to the next challenge in theoretical studies of manganites, namely a frontal computational attack of the colossal magnetoresistance phenomenon using double-exchange-like models, on large clusters, and including quenched disorder.« less
  • he one- and two-orbital double-exchange models for manganites are studied using Monte Carlo computational techniques in the presence of a robust electron-phonon coupling (but neglecting the antiferromagnetic exchangemore » $$J_{\rm AF}$$ between the localized spins). The focus in this effort is on the analysis of charge transport. Our results for the one-orbital case confirm and extend previous recent investigations that showed the presence of robust peaks in the resistivity vs. temperature curves for this model. Quenched disorder substantially enhances the magnitude of the effect, while magnetic fields drastically reduce the resistivity. A simple picture for the origin of these results is presented. It is also shown that even for the case of just one electron, the resistance curves present metallic and insulating regions by varying the temperature, as it occurs at finite electronic density. Moreover, in the present study these investigations are extended to the more realistic two-orbital model for manganites. The transport results for this model show large peaks in the resistivity vs. temperature curves, located at approximately the Curie temperature, and with associated large magnetoresistance factors. Overall, the magnitude and shape of the effects discussed here closely resemble experiments for materials such as $$\rm La_{0.70} Ca_{0.30} Mn O_{3}$$, and they are in qualitative agreement with the current predominant theoretical view that competition between a metal and an insulator, enhanced by quenched disorder, is crucial to understand the colossal magnetoresistance (CMR) phenomenon.« less
  • The one- and two-orbital double-exchange models for manganites are studied using Monte Carlo computational techniques in the presence of a robust electron-phonon coupling
  • No abstract prepared.
  • The temperature dependence of the electronic and atomic structure of the colossal magnetoresistive oxides La1 xSrxMnO3 (x = 0.3, 0.4) has been studied using core and valence level photoemission, x-ray absorption and emission, and extended x-ray absorption fine structure spectroscopy. A dramatic and reversible change of the electronic structure is observed on crossing the Curie temperature, including charge localization on and spin-moment increase of Mn, together with Jahn-Teller distortions, both signatures of polaron formation. Our data are also consistent with a phase-separation scenario.