Spin-glass state in CuGa2O4 - art. no. 184425

Magnetic susceptibility, magnetization, specific-heat, and positive muon sp in relaxation (mu SR) measurements have been used to characterize the magne tic ground state of the spinel compound CuGa2O4. We observe a spin-glass tr ansition of the S = 1/2 Cu2+ spins below T-f = 2.5 K characterized by a cus p in the susceptibility curve which is suppressed when a magnetic field is applied. We show that the magnetization of CuGa2O4 depends on the magnetic history of the sample. Well below T-f, the muon signal resembles the dynami cal Kubo-Toyabe expression reflecting that the spin freezing process in CuG a2O4 results in a Gaussian distribution of the magnetic moments. By means o f Monte Carlo simulations, we obtain the relevant exchange integrals betwee n the Cu2+ spins in this compound.