Electrical transport and magnetoresistance properties in (1 − x)La2/3Ca1/3MnO3/xSb2O5 composites

✍ Scribed by J.H. Miao; S.L. Yuan; G.M. Ren; X. Xiao; G.Q. Yu; Y.Q. Wang; S.Y. Yin

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 475 KB
• Volume: 136
• Category: Article
• ISSN: 0921-5107
• DOI: 10.1016/j.mseb.2006.09.007

✦ Synopsis

The composites with the nominal composition of (1x)La 2/3 Ca 1/3 MnO 3 (LCMO)/xSb 2 O 5 were fabricated, and their electrical transport and magnetoresistance (MR) behavior were investigated. Experimental results show that the metal-insulator transition temperature (T MI ) and resitivity (ρ) of the composites are largely dependent on Sb 2 O 5 addition level x. T MI shifts downwards and ρ increases with the increase of x at the range of x ≤ 3%, but T MI shifts upwards and ρ decreases with further increasing of x ≥ 3%. The high temperature (T > T MI ) semi-conducting part of the ρ data follow a small polaron hopping (SPH) conduction mechanism, and the metallic behavior of the samples (T < T MI ) fits the model in terms of electron-magnon scattering of the carriers. Furthermore, the MR effect can be largely enhanced over a wide temperature range in the composites compared with pure LCMO. At 3 T field, the MR rises from a base value ∼46%, for pure LCMO, to a maximum value of ∼86.7% for the case of x = 3%. It is argued that the enhancement of MR effect is attributed to the enhanced spin-polarized tunneling, which is manipulated by magnetic disorder especially at LCMO grain boundaries caused by Sb 2 O 5 addition.