Transport and magnetotransport properties of cold-pressed CrO2 powder, prepared by hydrothermal synthesis

JOURNAL OF ALLOYS AND COMPOUNDS

卷:479

Article

Belevtsev, B. I.¹  Dalakova, N. V.¹  Osmolowsky, M. G.²  Beliayev, E. Yu.¹  Selutin, A. A.² 

[1] Natl Acad Sci, B Verkin Inst Low Temp Phys & Engn, UA-61103 Kharkov, Ukraine

[2] St Petersburg State Univ, Dept Chem, St Petersburg 198504, Russia

关键词: Half metals;    Chemical synthesis;    Grain boundaries;    Magnetoresistance;    Magnetic measurements;   

DOI  :  10.1016/j.jallcom.2008.12.082

来源: Elsevier

【 摘 要 】

Submicron powder of CrO2 was prepared by hydrothermal synthesis method from chromium trioxide with use of special modifiers, which govern the growth of particles. Particles obtained were of rounded form with mean diameter about 120 nm. The powder (stabilized with thin surface layer of beta-CrOOH) has been characterized by structural, X-ray and magnetic measurements. The powder under investigation (with Curie temperature about 385 K) was cold-pressed and its transport and magnetotransport proper-ties have been measured in the temperature range 4-450 K in magnetic field up to 1.6 T. The samples studied is characterized by non-metallic temperature behavior of resistance and large negative magnetoresistance (MR) in low temperature range. At T = 5 K the MR magnitude has been -17% at H = 0.3 T and -20% at H = 1.4T. Its magnitude decreased fast with increase in temperature reducing to 0.3% and less for T > 200 K. It is shown that this MR behavior is inherent for a system of magnetic grains with spin-dependent intergrain tunnelling. Some peculiarities of MR behavior in low-temperature range (below 40 K) can be associated with percolating character of tunnelling conductivity of this granular system under conditions of availability of only few conducting current paths through the sample. (C) 2008 Elsevier B.V. All rights reserved.

【 授权许可】

Free