Critical exponents and irreversibility lines of La0.9Sr0.1CoO3 single crystal

We have studied the dynamic and static critical behavior of spin glass transition in insulating La0.9Sr0.1CoO3 single crystal by ac susceptibility and dc magnetization measurements in the vicinity of its freezing temperature (T-f). The dynamic scaling analysis of the frequency dependence of ac susceptibility data yields the characteristic time constant tau(0) = 1.6(9) x 10(-12) s, the dynamic critical exponent z nu = 9.5(2), and a frequency dependence factor K = Delta T-f/T-f(Delta log f) = 0.017, indicating that the sample enters into a canonical spin-glass phase below T-f = 34.8(2) K. The scaling analysis of non-linear magnetization in the vicinity of T-f through the static scaling hypothesis yields critical exponents beta = 0.89(1) and gamma = 2.9(1), which match well with that observed for well known three-dimensional (3D) Heisenberg spin glasses. From the longitudinal component of zero-field-cooled and field-cooled magnetization measurement, we have constructed the H-T phase diagram which represents the field evolution of two characteristic temperatures: the upper one, T-w(H), indicates the onset of spin freezing in a uniform external field H, while the lower one, T-s(H), marks the onset of strong irreversibility of the frozen state. The low field T-s(H) follows the critical line suggested by d'Almeida-Thouless model for canonical spin glass, whereas the T-w(H) exhibits a re-entrant behavior with a maximum in the T-w(H) at a nonzero field above which it follows the Gabay-Toulouse (GT) critical line which is a characteristic of Heisenberg spin glass. The reentrant behavior of the GT line resembles that predicted theoretically for n-component vector spin glasses in the presence of a uniaxial anisotropy field. (C) 2013 AIP Publishing LLC.