Random-singlet-like state emergent in s = 5/2 frustrated cubic lattice

We employ thermodynamic and electron spin resonance (ESR) techniques to elucidate the effects of quenched disorder on a ground state of s=5/2 frustrated cubic antiferromagnet La _3 Sb _3 Mn _2 O _14 . We observe the development of multiple ESR lines for temperatures below 80 K. Concomitantly, the ESR linewidth exhibits a power-law increase, accompanied by an intriguing shift in resonance fields. These observations point to the occurrence of inhomogeneous magnetism. Additionally, ac magnetic susceptibility and magnetization data obey a scaling relation of χ '(H,T) and M ( H , T ) in μ _BH/k_BT with the scaling exponent α =0.53 . This scaling behavior alludes to the formation of a random-singlet-like state and the presence of abundant low-lying excitations. Our results highlight the concerted interplay of strong disorder and frustration to stabilize a putative random-singlet state even in classical and high-dimensional spin systems.