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Title: Positive magnetoresistance in Ca-doped cobaltites

Transport properties of polycrystalline La{sub 1−x}Ca{sub x}CoO{sub 3} (0.10 ≤ x ≤ 0.25) are systemically studied in this work. Three types of magnetoresistance (MR) effects are found in the Ca-doped cobaltites. Two negative MRs appear around high-temperature ferromagnetic transition and at low temperatures, which correspond to the conventional MR due to the field-induced suppression of spin-disorder scattering and the intergranular giant-MR due to spin-dependent transport between the ferromagnetic clusters, respectively. More interestingly, another exotic positive MR emerges at intermediate temperature region, which had not been previously reported in Sr- and Ba-doped cobaltites. It is found that this positive MR is associated with an abnormally magnetic transition and increases with the increase of x. For x = 0.25, the MR at low temperatures is dominated by the positive one, which is isotropic and nearly linear with the magnetic field. The possible origin of the positive MR in the Ca-doped cobaltites is discussed.
Authors:
; ; ; ;  [1]
  1. Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)
Publication Date:
OSTI Identifier:
22395483
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BARIUM COMPOUNDS; CALCIUM COMPOUNDS; COBALT OXIDES; CONCENTRATION RATIO; DOPED MATERIALS; FERROMAGNETIC MATERIALS; FERROMAGNETISM; LANTHANUM COMPOUNDS; MAGNETIC FIELDS; MAGNETORESISTANCE; POLYCRYSTALS; SCATTERING; SPIN; STRONTIUM COMPOUNDS