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 \(s=5/2\) $s=5/2$ frustrated cubic antiferromagnet La \(_3\) ${}_3$ Sb \(_3\) ${}_3$ Mn \(_2\) ${}_2$ O \(_{14}\) ${}_{14}$ . 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 \(\chi '(H,T)\) ${\chi }^{\prime }(H,T)$ and M(H, T) in \(\mu _{\textrm{B}}H/k_{\textrm{B}}T\) ${\mu }_{\text{B}}H/k_{\text{B}}T$ with the scaling exponent \(\alpha =0.53\) $\alpha =0.53$ . 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.