The chiral anomalous Hall effect at high magnetic fields in Au-Fe alloys

摘要

The Hall effect of the disordered and frustrated magnetic alloys Au-Fe 8 at% and Au-Fe 18 at% was studied in applied magnetic fields up to 14 T. The measurements were carried out in fixed temperatures spanning the spin glass and paramagnetic phases of Au-Fe 8 at% and in the reentrant, ferromagnetic and paramagnetic states in Au-Fe 18 at%. The experiments confirm the occurrence of a large contribution from spin chiralities to the anomalous Hall effect (AHE) in both systems, either in the spin glass and the canted ferromagnetic phases. The amplitude of the chirality-driven term is progressively attenuated as the field intensity is increased. This effect is consistent with the expected field-induced closing of the solid angle defining scalar spin chirality. Evidence for the occurrence of a chiral contribution to AHE was also detected in the paramagnetic phases of the two studied systems, showing that this term persists as long as the typical time scale for the spin dynamics is significantly larger than the transport relaxation time.