Cluster spin-glass behavior in Ni2In-type Mn–Cu-Ga alloys

Abstract

We report the structural and magnetic properties of Ni2In-type (Mn0.75Cu0.25)66Ga34 alloy by using powder X-ray diffraction, DC- and AC-susceptibility, aging effect and magnetic memory effect measurements. From the results of the DC-susceptibility measurements, an irreversible temperature Tirr(0) = 109.1 ± 1.4 K and a crossover exponent Φ = 4.9 ± 0.3 are obtained, which indicate that our system favors a canonical Heisenberg spin-glass state. From the AC-susceptibility results, the shift of freezing temperature with frequency is characterized by a medium Mydosh parameter of 0.03. Furthermore, a relaxation time of the spin flip τ0=1.1×10−9 s and a critical exponent zv=7.5 are obtained by the fitting of power law. A significant aging effect and a magnetic memory effect in both zero-field-cooled and field-cooled protocols are observed. In addition, the memory effect existing in a negative T cycle but missing in a positive T cycle favors the hierarchical model in our sample. All the above observations render a cluster spin-glass behavior in (Mn0.75Cu0.25)66Ga34 alloy.