Magnetostriction of SmFeO₃and YFe_1-<i>x</i>Co_<i>x</i>/2Ti_<i>x</i>/2O₃in the Spin Reorientation Region

Abstract

Longitudinal and transverse magnetostrictions along the a, b and c axes of SmFeO3 and YFe1-xCox/2Tix/2O3 (0.004≦x≦0.012) were measured. In both of the orthoferrites, the magnetostriction increases in magnitude near the spin reorientation temperature region, reaching maximum value of Δl/l∼15×10-6 under an external field of 6.8 kOe. The crystals are elongated along the c axis while contracted along the a and b axes when the spontaneous magnetization is rotated from the a toward the c axis by applying the external field, and are distorted in the opposite direction when the magnetization is reversed. It was shown that the magnetostriction of SmFeO3 is roughly proportional to the field induced rotation angle of the magnetization, which is calculated using the empirical magnetic free energy expression. The origin for the magnetostriction is discussed.