dc magnetization measurements in Eu2CuO4:Gd3+

Abstract

Dc magnetization measurements in a Gd doped Eu₂CuO₄ single crystal indicate the appearance below T_N=243 K, of a weak ferromagnetic component M_s(T), in addition to the Van Vleck paramagnetism of the Eu³⁺ ions. M_s(T) is oriented parallel to the (001) plane and its magnitude and in‐plane angular dependence are strongly dependent on the cooling conditions. For samples cooled in zero magnetic field the magnetization is isotropic in the (001) plane with M_s(0)=2.2(4)×10⁻³ μ_B/formula unit. For samples cooled in a field (FC), M_s(T) increases as a function of the field applied for cooling, H_FC, reaching M_s(0)=5.0(5)×10⁻³ μ_B/formula unit for H_FC=10 kG. A uniaxial magnetic anisotropy develops in this case with an easy axis along the [110] crystallographic direction lying closer to the orientation of H_FC. A magnetic free energy including second and fourth order in‐plane anisotropy terms provides a good description of the experimental results, with H⁽²⁾=−85(5) G and H⁽⁴⁾=10(3) G.