Spin-Glass State in $\mathrm{CuG}{\mathrm{a}}_2{\mathrm{O}}_4$

Abstract

Magnetic susceptibility, magnetization, specific heat and positive muon spin relaxation (\musr) measurements have been used to characterize the magnetic ground-state of the spinel compound $\mathrm{CuG}{\mathrm{a}}_2{\mathrm{O}}_4$. We observe a spin-glass transition of the S=1/2 $\mathrm{C}{\mathrm{u}}^{2+}$ spins below ${\mathrm{T}}_{\mathrm{f}}=2.5K$ characterized by a cusp in the susceptibility curve which suppressed when a magnetic field is applied. We show that the magnetization of $\mathrm{CuG}{\mathrm{a}}_2{\mathrm{O}}_4$ depends on the magnetic histo Well below ${\mathrm{T}}_{\mathrm{f}}$, the muon signal resembles the dynamical Kubo-Toyabe expression reflecting that the spin freezing process in $\mathrm{CuG}{\mathrm{a}}_2{\mathrm{O}}_4$ results Gaussian distribution of the magnetic moments. By means of Monte-Carlo simulati we obtain the relevant exchange integrals between the $\mathrm{C}{\mathrm{u}}^{2+}$ spins in this compound.

6 pages, 16 figures