Observation of spin glass behavior in Ba0.8La0.2Ti0.8Co0.2O3
Key Laboratory of Materials Physics, Institute of Solid State
Physics, Chinese Academy of Sciences, P.O. Box 1129, Hefei
230031, Anhui Province, P.R.
2 High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P.R. China
Received in final form: 15 February 2012
Published online: 16 May 2012
The structural and magnetic properties of Ba0.8La0.2Ti1−xCoxO3 (0 ≤ x ≤ 0.2) have been investigated. All samples show a cubic structure with the space group of Pm3m at room temperature. Ba0.8La0.2TiO3 exhibits a carrier induced Pauli-paramagnetism and Ba0.8La0.2Ti0.9Co0.1O3 shows a Curie-Weiss like paramagnetism. With increasing cobalt doping, Ba0.8La0.2Ti0.8Co0.2O3 seems to undergo a spin glass like transition at Tf = 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 τr and the critical exponent n deduced from the function show opposite tendencies below and above Tf, and the possible reason has been discussed. n at Tf close to 2/3 suggests that Ba0.8La0.2Ti0.8Co0.2O3 may be a three dimensional Ising spin glass.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2012