Irreversibility crossover in the H-T phase diagram of a Cd1-xMnxTe spin glass

We have measured the longitudinal component of the zero-field-cooled and held-cooled magnetization of the compound Cd0.62Mn0.38Te between 10 and 400 G in the temperature range 7-11 K. The irreversible magnetization shows two distinct regimes depending on field, from which Mr determine the H-T phase diagram. A crossover from Ising to Heisenberg behavior is found near 100 G, with evidence in the hihg-field region of a Gabay-Toulouse line characteristic of Heisenberg spin glasses. The existence of a weak anisotropic Dzyaloshinsky-Moriya interaction due to the superexchange mechanism explains thc observed behavior.