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Colossal Magnetoresistance in Manganites as a Multicritical Phenomenon

2003; American Physical Society; Volume: 90; Issue: 19 Linguagem: Inglês

10.1103/physrevlett.90.197201

1092-0145

Shuichi Murakami, Naoto Nagaosa,

Advanced Condensed Matter Physics

The colossal magnetoresistance in manganites $A{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$ is studied from the viewpoint of multicritical phenomena. To understand the complicated interplay of various phases, we study the Ginzburg-Landau theory in terms of both the mean-field approximation and the renormalization-group analysis for comparison with the observed phase diagram. Several novel features, such as the first-order ferromagnetic transition and the dip in the transition temperature near the multicritical point, can be understood as being driven by enhanced fluctuations near the multicritical point. Furthermore, we obtain a universal scaling relation for the $H/M$ versus ${M}^{2}$ plot (Arrott plot), which fits rather well with the experimental data, providing further evidence for the enhanced fluctuation.