Nd3+ induced twofold continuous spin reorientation transition and magnetization along the b-axis in a Dy0.9Nd0.1FeO3 single crystal

Abstract

Rare-earth orthoferrites have attracted intensive attention in the last few years for their abundant physical capabilities. In the present paper, a Nd³⁺ doped Dy_0.9Nd_0.1FeO₃ (DNFO91) single crystal with high quality was grown by an optical floating zone method, and the magnetic properties have been investigated. We report an intriguing hybrid magnetic configuration Γ₄₊₃ consisting of Γ₄(G_x, A_y, F_z) and Γ₃(C_x, F_y, A_z), and it has a non-zero spontaneous magnetic moment along both the b-axis and c-axis. With lowering the temperature, the DNFO91 crystal experiences two continuous spin reorientation transitions from Γ₄₊₃ to Γ₂ at 45 K and finally to Γ₁ below 43.8 K; here, Γ₂ is an incomplete metastable phase transition induced by a magnetic field and disappears at 5000 Oe. Further research directly distinguished the rare-earth ion contributions for the first time, the magnetization along the b-axis originates from Nd³⁺ while that along the a-axis comes from Dy³⁺, and the relative strength can be further manipulated with an applied magnetic field. An exchange bias behavior was also observed in the M–H curves, revealing the exchange interaction between Dy³⁺/Nd³⁺ sublattices and Fe³⁺ sublattices. These features of single-crystal DNFO91 can help understand the influence of rare-earth doping on the magnetic structure and physical phenomenon in RFeO₃, and this crystal has great application potential.