Magnetic and structural properties of the solid solution CuAl2(1-x) Ga2xO4

CuAl2O4 is a ternary oxide spine! with Cu2+ ions (s = 1/2) primarily populating the A-site diamond sublattice. The compound is reported to display evidence of spin glass behavior but possess a non-frozen magnetic ground state below the transition temperature. On the other hand, the spinel CuGa2O4 displays spin glass behavior at similar to 2.5 K with Cu2+ ions more readily tending to the B-site pyrochlore sublattice. Therefore, we investigate the magnetic and structural properties of the solid solution CuAl2(1-x)Ga2xO4 examining the evolution of the magnetic behavior as Al3+ is replaced with a much larger Ga3+ ion. Our results show that the Cu2+ ions tend to migrate from tetrahedral to octahedral sites as the Ga3+ ion concentration increases, resulting in a concomitant change in the glassy magnetic properties of the solution. Results indicate glassy behavior for much of the solution with a general trend towards decreasing magnetic frustration as the Cu2+ ion shifts to the B-site. However, the x = 0.1 and 0.2 members of the system do not show glassy behavior down to our measurement limit (1.9 K) suggesting a delayed spin glass transition. We suggest that these two members are additional candidates for investigation to access highly frustrated exotic quantum states.

Automated summary

The study investigates the magnetic and structural properties of the solid solution CuAl2(1-x)Ga2xO4, demonstrating a shift in Cu2+ ions from tetrahedral to octahedral sites with increasing Ga3+ ion concentration. While most of the solution exhibits glassy behavior, the trend is towards decreasing magnetic frustration as the Cu2+ ion moves to the B-site, with exceptions in the x = 0.1 and 0.2 members which show delayed spin glass transition. These members are suggested as additional candidates for investigating highly frustrated exotic quantum states.