Coexistence of magnetic and dielectric glassy states in alternating kagome and triangular lattice LuBaCo₄O₇ cobaltite

To date, the alternating kagome and triangular lattice cobaltites, i.e., RBaCo₄O₇ (R = Ca, Y and rare earth) have been well-studied due to their large structural distortions, anisotropic exchange interactions, chiral spin liquid states, and giant multiferroic properties. Here, we report the co-existence of magnetic and dielectric glassy states in LuBaCo₄O₇ cobaltite below 50 K. AC magnetization studies show an absence of conventional spin freezing phenomena. The cooling and heating in unequal field (CHUF), thermal cycling of magnetization and time dependent magnetization studies at the low temperature (T ) show the presence of the magnetic glassy state. The T dependent dielectric constant (ε) exhibits a strong frequency independent response at the first order structural phase transition temperature T = 160 K; (trigonal P 31c to monoclinic Cc) and also significant features at the T ≈ 110 K (monoclinic Cc to orthorhombic P bn2₁) phase transition. Further, 0shows a frequency independent peak at 43 K (P bn2₁) and also diploar glassy features below 20 K (Cc). The non-equilibrium magnetic glassy dynamics and diploar glassy state at low-T arises from the kinetic arrest of Cc and P bn2₁ phases. From the dielectric probe we are able to clearly distinguish the kinetically arrested phases at low-T , whereas the bulk magnetization studies unable to do as the arrested phases have low magnetic moments.