Static and dynamic signatures of anisotropic electronic phase separation in La2/3Ca1/3MnO3 thin films under anisotropic strain

Article

关键词: MAGNETIC VISCOSITY;    DOPED MANGANITES;    COLOSSAL MAGNETORESISTANCE;    LA0.7CA0.3MNO3 FILMS;    DOUBLE EXCHANGE;    LA0.5CA0.5MNO3;    PEROVSKITES;    COEXISTENCE;    TRANSITION;    PHYSICS;   

DOI  :  10.1103/PhysRevB.97.214428

来源: SCIE

【 摘 要 】

The electronic phase separation (EPS) of optimally doped La2/3Ca1/3MnO3 (LCMO) thin films under various degrees of anisotropic strain is investigated by static magnetotransport and dynamic relaxation measurements. Three LCMO films were grown simultaneously on (001) NdGaO3 substrates by pulsed laser deposition, and then postgrowth annealed at 780 degrees C in O-2 for different durations of time. With increasing annealing time, the films developed significant strains of opposite signs along the two orthogonal in-plane directions. The static temperature-dependent resistivity, p(T), was measured simultaneously along the two orthogonal directions. With increasing annealing time, both zero-field-cooled and field-cooled p(T) show significant increases, suggesting strain-triggered EPS and appearance of antiferromagnetic insulating (AFI) phases in a ferromagnetic metallic (FMM) ground state. Meanwhile, p(T) along the tensile-strained [010] direction becomes progressively larger than that along the compressive-strained [100]. The enhanced resistivity anisotropy indicates that the EPS is characterized by phase-separated FMM entities with a preferred orientation along [100], possibly due to the cooperative deformation and rotation/tilting of the MnO6 octahedra under the enhanced anisotropic strain. The anisotropic EPS can also be tuned by an external magnetic field. During a field cycle at several fixed temperatures, the AFI phases are melted at high fields and recovered at low fields, resulting in sharp resistance changes of ratio as high as 10(4). Furthermore, the resistivity was found to exhibit glasslike behavior, relaxing logarithmically in the phase-separated states. Fitting the data to a phenomenological model, the resulting resistive viscosity and characteristic relaxation time are found to evolve with temperature, showing a close correlation with the static measurements in the EPS states.

【 授权许可】

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