Heisenberg spin-glass behaviour in Ga 0.99 Yb 0.01 FeO 3
Résumé
The dynamic and static magnetic properties of Ga0.99Yb0.01FeO3 are studied in detail using ac susceptibility and dc magnetization measurements. The study shows that the compound undergoes a spin-glass freezing at . The dynamic scaling analysis of ac susceptibility data reveals typical features characteristic of canonical spin-glasses, i.e., relaxation time , critical exponent , and frequency sensitivity parameter within three frequency decades. The analysis of the critical behaviour of the static nonlinear susceptibility yields the critical exponents , and , which lie between those typical of three-dimensional (3D) weakly anisotropic Heisenberg and Ising spin glasses. The analysis of the field-cooled and zero-field-cooled magnetization data allows to define two characteristic temperatures depending on the applied magnetic field. The upper one, , is the threshold temperature corresponding to the appearance of weak irreversibility, whereas the lower one, , marks the onset of strong irreversibility. The resulting field-temperature phase diagram turns out to be in good quantitative agreement with the mean-field predictions for 3D Heisenberg spin-glass with random magnetic anisotropy, and appears consistent with the chiral driven freezing scenario.