Interplay between double-exchange, superexchange, and Lifshitz localization in doped manganites



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Alonso, J. L. and Fernández Pérez, Luis Antonio and Guinea, F. and Laliena, V. and Martín Mayor, Víctor (2002) Interplay between double-exchange, superexchange, and Lifshitz localization in doped manganites. Physical review B, 66 (10). ISSN 1098-0121

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Considering the disorder caused in manganites by the substitution Mn→Fe or Ga, we accomplish a systematic study of doped manganites begun in previous papers. To this end, a disordered model is formulated and solved using the variational mean-field technique. The subtle interplay between double exchange, superexchange, and disorder causes similar effects on the dependence of T_(C) on the percentage of Mn substitution in the cases considered. Yet, in La_(2/3)Ca_(1/3)Mn_(1-y)Ga_(y)O_(3) our results suggest a quantum critical point (QCP) for y ≈ 0.1–0.2, associated to the localization of the electronic states of the conduction band. In the case of La_(x)Ca_(x)Mn_(1-y)Fe_(y)O_(3) (with x = 1/3,3/8) no such QCP is expected.

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© 2002 American Physical Society. We thank P. A. Algarabel, J. Blasco, J. García, R. Ibarra, J. M. de Teresa, and especially Domingo González, for discussions. The authors acknowledge financial support from CICyT (Spain) through Grant Nos. PB96-0875, AEN99- 0990, FPA2000-0956, and FPA2000-1252. V.M.-M. was supported by E.C. Contract No. HPMF-CT-2000-00450.

Uncontrolled Keywords:Colossal magnetoresistance; Phase-diagram; Systems; Model; Perovskites; Transition; Behavior; Physics; Fe.
Subjects:Sciences > Physics
Sciences > Physics > Physics-Mathematical models
ID Code:38667
Deposited On:09 Aug 2016 10:12
Last Modified:09 Aug 2016 10:43

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