Crystal structure, thermodynamic properties, and adiabatic demagnetization refrigeration (ADR) effect in the spin-7/2 triangular antiferromagnet KBaGd(BO3)2 are reported. With the average nearest-neighbor exchange coupling of 44 mK, this compound shows magnetic order below $T_N = 263$\,mK in zero field. The ADR tests reach the temperature of $T_{ min} = 122$ mK, more than twice lower than $T_N$, along with the entropy storage capacity of 192 mJK$^{ -1}$cm$^{ -3}$ and the hold time of more than 8 hours in the PPMS setup, both significantly improved compared to the spin-1/2 Yb$^{ 3+}$ analog. We argue that KBaGd(BO3)2 shows a balanced interplay of exchange and dipolar couplings that together with structural randomness and geometrical frustration shift $T_{ min}$ to well below the ordering temperature $T_N$, therefore facilitating the cooling.
Categories: cond-mat.str-el cond-mat.mtrl-sci