Indications of quantum fluctuations in magnetically frustrated Gd2GaSbO7 and Gd2InSbO7 pyrochlores

Abstract

Gd₂GaSbO₇ (GGSO) and Gd₂InSbO₇ (GISO) pyrochlore compounds are investigated as potential candidates for exhibiting quantum fluctuations in a spin-ice-like state. These materials, less explored in magnetic frustration, were synthesized and structurally confirmed via X-ray diffraction. Magnetic and heat capacity measurements revealed no long-range order down to 400 mK. The low-temperature magnetic heat capacity shows broad maxima around T_max = 0.9 K and T_max = 1 K for GGSO and GISO respectively, with power-law dependence $\left(C_{\mathrm{mag}}\approx T^{d/n}\right)$ yielding exponents, T^1.71 for GGSO and T^1.49 for GISO, indicating spin fluctuations at low temperatures. GGSO and GISO retain residual entropy akin to water ice, indicative of spin-ice behavior. Notably, GISO has the weakest exchange interaction among Gd-based pyrochlores, which may be influenced by chemical pressure and exchange pathways. These findings highlight significant spin fluctuations and potential quantum effects, contrasting with long-range order in other Gd-pyrochlores and aligning with quantum spin-ice candidates like Pr₂Zr₂O₇ and Yb₂GaSbO₇.