Suppression of Ferromagnetic Double Exchange by Vibronic Phase Segregation

Abstract

From Raman spectroscopy, magnetization, and thermal-expansion on the system La2/3(Ca1-xSrx)1/3MnO3, we have been able to provide a quantitative basis for the heterogeneous electronic model for manganites exhibiting colossal magnetoresistance (CMR). We construct a mean-field model that accounts quantitatively for the measured deviation of TC(x) from the TC predicted by de Gennes double exchange in the adiabatic approximation, and predicts the occurrence of a first order transition for a strong coupling regime, in accordance with the experiments. The existence of a temperature interval TC<T<T* where CMR may be found is discussed, in connection with the occurrence of an idealized Griffiths phase.

arXiv commentReplaced with the final version accepted in Physical Review Letters

References in corpus (4)

• Colossal Effects in Transition Metal Oxides Caused by Intrinsic Inhomogeneities
• Colossal Magnetoresistance is a Griffiths Singularity
• Raman phonons as a probe of disorder, fluctuations and local structure in doped and undoped orthorhombic and rhombohedral manganites
• Evidence for charge localization in the ferromagnetic phase of La_(1-x)Ca_(x)MnO_3 from High real-space-resolution x-ray diffraction

Cited by in corpus (8)

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• Direct Correlation between 1/f-magneto-noise and magnetoresistance in La0.7Sr0.3MnO3 and (La0.5Pr0.2)Ba0.3MnO3 manganites
• A phenomenological model for the pressure sensitivity of the Curie temperature in hole-doped manganites
• Ginzburg-Landau theory for the magnetic and structural transitions in La${}_{1-y}$(Ca${}_{1-x}$Sr${}_x$)${}_y$MnO${}_3$
• Ab initio study of the influence of nanoscale doping inhomogeneities in the phase separated state of La${}_{1-x}$Ca${}_x$MnO${}_3$