Cluster-glass behaviour and large magnetocaloric effect in frustrated hyperkagome ferromagnet Li$_2$MgMn$_3$O$_8$

• DOI: 10.48550/arxiv.2406.17623
• Publication Date: 2024-06-25
• Authors: R. Kolay; A. Magar; Alexander A. Tsirlin; R. Nath
• Keywords: Magnetic refrigeration

A detailed study of the structural and magnetic properties spin-$3/2$ hyperkagome lattice compound Li$_2$MgMn$_3$O$_8$ is reported. This material shows ferromagnetic response below $T_{\rm C} \simeq 20.6$ K, temperature almost three times lower than Curie-Weiss $\theta_{\rm CW} 56.6$ K. Density-functional band-structure calculations suggest that this reduction in C}$ may be caused by long-range antiferromagnetic couplings frustrate nearest-neighbor on lattice. Large magnetocaloric effect observed around with a maximum value isothermal entropy change $\Delta S_{\rm m}\simeq 20$ J/kg-K relative cooling power $RCP\simeq 840$ J/kg for 7 T field change. Critical analysis magnetization data scaling 3D Heisenberg/XY universality class transition. The DC AC measurements further reveal glassy nature non-equilibrium dynamics via relaxation memory demonstrates system evolves through large number intermediate metastable states manifests significant cluster-glass state.