Cépas, O. ; Krishnamurthy, H. R. ; Ramakrishnan, T. V. (2006) Instabilities and insulator-metal transitions in half-doped manganites induced by magnetic-field and doping Physical Review B: Condensed Matter and Materials Physics, 73 (3). 035218_1-035218_20. ISSN 1098-0121
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Official URL: http://prb.aps.org/abstract/PRB/v73/i3/e035218
Related URL: http://dx.doi.org/10.1103/PhysRevB.73.035218
Abstract
We discuss the phase diagram of the two-orbital model of half-doped manganites by calculating self-consistently the Jahn-Teller (JT) distortion patterns, charge, orbital and magnetic order at zero temperature. We analyze the instabilities of these phases caused by electron or hole doping away from half-doping, or by the application of a magnetic-field. For the CE insulating phase of half-doped manganites, in the intermediate JT coupling regime, we show that there is a competition between canting of spins (which promotes mobile carriers) and polaronic self-trapping of carriers by JT defects. This results in a marked particle-hole asymmetry, with canting winning only on the electron doped side of half-doping. We also show that the CE phase undergoes a first-order transition to a ferromagnetic metallic phase when a magnetic-field is applied, with abrupt changes in the lattice distortion patterns. We discuss the factors that govern the intriguingly small scale of the transition fields. We argue that the ferromagnetic metallic phases involved have two types of charge carriers, localized and bandlike, leading to an effective two-fluid model.
Item Type: | Article |
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Source: | Copyright of this article belongs to The American Physical Society. |
ID Code: | 40789 |
Deposited On: | 25 May 2011 11:19 |
Last Modified: | 17 May 2016 22:44 |
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