Magnetotransport properties of La1-xCaxMnO3 (0.52 ≤x≤ 0.75): Signature of phase coexistence

THIN SOLID FILMS

卷:631

Article

Culo, M.¹  Basletic, M.²  Tafra, E.²  Hamzic, A.²  Tomic, S.¹  Fischgrabe, F.³  Moshnyaga, V.³  Korin-Hamzic, B.¹ 

[1] Inst Fiziku, POB 304, HR-10001 Zagreb, Croatia

[2] Univ Zagreb, Fac Sci, Dept Phys, POB 331, HR-10001 Zagreb, Croatia

[3] Georg August Univ Gottingen, Phys Inst 1, Friedrich Hund Pl 1, D-37077 Gottingen, Germany

关键词: Manganites;    Charge order;    Magnetotransport;    Variable-range hopping;    CMR;    Phase coexistence;   

DOI  :  10.1016/j.tsf.2017.04.027

来源: Elsevier

【 摘 要 】

We report the temperature and magnetic field dependence of transport properties in epitaxial films of the manganite La1-xCaxMnO3 in the overdoped region of the phase diagram for x > 0.5, where a chargeordered ( CO) and an antiferromagnetic (AF) phase are present. Resistivity, magnetoresistance and angular dependence of magnetoresistance were measured in the temperature interval 4.2K < T < 300K, for three concentrations x = 0.52, 0.58 and 0.75 and in magnetic fields up to 5 T. The semiconductor/insulator-like behavior in zero field was observed in the entire temperature range for all three concentrations x and the electric conduction, at lower temperatures, in the CO state obeys 3D Mott's variable-range hopping model. A huge negative magnetoresistance for x = 0.52 and x = 0.58, a metal-insulator transition for B > 3T for x = 0.52 and the presence of anisotropy in magnetoresistance for x = 0.52 and x = 0.58 show the fingerprints of colossal magnetoresistance (CMR) behavior implying the existence of ferromagnetic (FM) clusters. The declining influence of the FM clusters in the CO/AF part of the phase diagram with increasing x contributes to a possible explanation that a phase coexistence is the origin of the CMR phenomenon. (C) 2017 Elsevier B.V. All rights reserved.

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