Dielectric anomaly at T_N in LaMnO₃ as a signature of coupling between spin and orbital degrees of freedom

Abstract

We observe a distinct anomaly in dielectric permittivity (ε′) as well as relaxation time (τ0) versus temperature (T) pattern at the antiferromagnetic transition point T_N in a single crystal of LaMnO₃. The equivalent circuit analysis of the impedance spectra across T_N reveals a clear anomaly in the capacitive component C₀ at T_N. Since no structural transition takes place across T_N, the anomaly in τ0 and C₀ at TN possibly signifies multiferroicity stemming from coupling between orbital and spin order in LaMnO₃.