Coexistence of magnetic and dielectric glassy states in alternating kagome and triangular lattice LuBaCo4 O7 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 coexistence 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 dielectric constant (ϵ′) exhibits a strong frequency-independent response at 45 K and dipolar glassy features below 20 K. The nonequilibrium magnetic glassy dynamics and dipolar glassy state at low T arises from the kinetic arrest of monoclinic (Cc) and orthorhombic (Pbn21) phases. From the dielectric probe, we are able to clearly distinguish the kinetically arrested phases at low T, whereas the bulk magnetization studies are unable to do so, as the arrested phases have low magnetic moments.