Single-domain-wall states in millimeter-scale samples of ErFeO3

Hysteresis loops in a 3.9x3.9x3.1 mm(3) single-crystal ErFeO3 sample were studied in the 4 < T < 70 K temperature interval. Above and near the compensation point T-comp=46 K the hysteresis loops are rectangular, with the coercive force diverging at T-comp. As the temperature is lowered toward the erbium ordering transition at T-N2=4.1 K, the shape of the loops experiences a dramatic change. First, the loops develop triangular tails. Then the triangles become prominent while the central rectangular part collapses. A double-loop hysteresis pattern with two triangular loops emerges. This behavior is explained by a reversible motion of a single magnetic domain wall in the sample. The simplicity of the magnetic state is related to the small magnetization and correspondingly large domain sizes in orthoferrites. Our model reproduces the correlation of the loops' shape with the temperature dependence of the total magnetic moment of ErFeO3.