Spin-reorientation, ferroelectricity and magnetodielectric effect in YFe_1−x Mn_xO₃ (0.1 ≤ x ≤ 0.40)

Abstract

We report the observation of magnetoelectric and magnetodielectric effects at different temperatures in Mn-substituted yttrium orthoferrite, YFe_1−x Mn_xO₃ (0.1 ≤ x ≤ 0.40). Substitution of Mn in antiferromagnetic YFeO₃ (T_N = 640  K) induces a first-order spin-reorientation transition at a temperature, T_SR, which increases with x whereas the Neel temperature (T_N) decreases. While the magnetodielectric effect occurs at T_SR and T_N, the ferroelectricity appears rather at low temperatures. The origin of magnetodielectric effect is attributed to spin-phonon coupling as evidenced from the temperature dependence of Raman phonon modes. The large magnetocapacitance (18% at 50 kOe) near T_SR = 320  K and high ferroelectric transition temperature (∼115  K) observed for x = 0.4 suggest routes to enhance magnetoelectric effect near room temperature for practical applications.