Eur. Phys. J. B (2012) 85: 156
https://doi.org/10.1140/epjb/e2012-20912-x

Regular Article

Observation of spin glass behavior in Ba_0.8La_0.2Ti_0.8Co_0.2O₃

¹ Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei 230031, Anhui Province, P.R. China
² High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P.R. China

^a e-mail: jyang@issp.ac.cn
^b e-mail: ypsun@issp.ac.cn

Received: 9 November 2011
Received in final form: 15 February 2012
Published online: 16 May 2012

Abstract

The structural and magnetic properties of Ba_0.8La_0.2Ti_1−xCo_xO₃ (0 ≤ x ≤ 0.2) have been investigated. All samples show a cubic structure with the space group of Pm3m at room temperature. Ba_0.8La_0.2TiO₃ exhibits a carrier induced Pauli-paramagnetism and Ba_0.8La_0.2Ti_0.9Co_0.1O₃ shows a Curie-Weiss like paramagnetism. With increasing cobalt doping, Ba_0.8La_0.2Ti_0.8Co_0.2O₃ seems to undergo a spin glass like transition at T_f = 10.1 K as evidenced by the frequency dependence of ac susceptibility measurements, aging effect measurements, memory effect measurements and magnetic relaxation measurements. The time decay of the thermoremnant magnetization can be well described with the stretched exponential function. It is worthwhile to note that the temperature dependence of relaxation characteristic time τ_r and the critical exponent n deduced from the function show opposite tendencies below and above T_f, and the possible reason has been discussed. n at T_f close to 2/3 suggests that Ba_0.8La_0.2Ti_0.8Co_0.2O₃ may be a three dimensional Ising spin glass.