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Electronic Structure and Conductivity Mechanism in Manganite Thin Films Exhibiting Colossal Magnetoresistance

Published online by Cambridge University Press:  02 July 2020

Kannan M. Krishnan
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA94720
Honglyoul Ju
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA94720
C. Nelson
Affiliation:
Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA94720
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Extract

Perovskite manganites, which have the the general formula R1-xAxMnO3 (R = La, Pr, or Nd and A = Ca, Sr, Ba, or Pb), have generated much recent interest because they exhibit “colossal magnetoresistance” (CMR), i.e. a small change in an applied magnetic field dramatically changes the electrical resistance of the material. Materials that exhibit this effect are being developed for various field-sensing applications but currently, the mechanism by which CMR occurs is not known. Conduction in these materials is explained by the “double exchange” mechanism, where the conductivity is attributed to electrons hopping back and forth between neighboring manganes ions. Such hopping is a maximum when the magnetic moments of the magnese ions are aligned parallel and a minimum when they are aligned antiparallel. In short, these materials show metallic conductivity when they are ferromagnetic and insulating behavior when they are antiferromagnetic. Moreover, they change from metallic to insulating behavior as a function of temperature.

Type
Microscopy of Semiconducting and Superconducting Materials
Copyright
Copyright © Microscopy Society of America

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References

1.Ju, H. L. and Kannan M., Krishnan, Solid State Communications, in pressGoogle Scholar
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3.Ju, H. L., Sohn, H.-C. and Kannan M., Krishnan, Physical Review Letters, 79 (1997) 3230CrossRefGoogle Scholar
4. This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Sciences Division of the U.S. Department of Energy under contract No. DEAC03-76SF00098.Google Scholar