Unconventional magnetic glassiness in non-centrosymmetric Sm$_7$Pd$_3$: Interplay of magnetic frustration, long-range order, and frozen domains

Abstract

We present a comprehensive investigation of the intricate spin dynamics in the non-centrosymmetric compound Sm$_7$Pd$_3$, revealing the coexistence of spin glass, domain glass, and ferromagnetic (FM) behaviors. Magnetic field-dependent measurements indicate large coercivity, suggesting ferromagnetic domain formation below the Curie temperature ($T_C \sim 173$ K), while temperature-dependent magnetization data point to antiferromagnetic (AFM) coupling, highlighting the competition between FM and AFM interactions. Detailed ac susceptibility, isothermal remanent magnetization, and aging effect measurements demonstrate the presence of two distinct types of glassiness in the sample, and their possible origins are discussed extensively. Magnetization measurements reveal the mixing of the J = 5/2 ground state of Sm$^{3+}$ with the excited J = 7/2 multiplet, lying 965 K above. The specific heat data show further crystalline electric field splitting of the J = 5/2 state into a ground-state doublet and a fourfold-degenerate excited state.