Probing magnetic anisotropy and spin-reorientation transition in the three-dimensional antiferromagnet Ho0.5Dy0.5FeO3|Pt using spin Hall magnetoresistance

Abstract

Orthoferrites (RFeO 3 ) containing rare-earth (R) elements are 3D antiferromagnets (AFMs) that exhibit characteristic weak ferromagnetism originating due to slight canting of the spin moments and display a rich variety of spin-reorientation transitions in the magnetic field (H )-temperature (T ) parameter space. We present spin Hall magnetoresistance (SMR) studies on a b plate (ac plane) of crystalline Ho 0.5 Dy 0.5 FeO 3 |Pt hybrid at various T in the range 11-300 K. In the room temperature 4 phase, the switching between two degenerate domains occurs at fields above a critical value, H c ≈ 713 Oe. Under H > H c , the angular dependence of SMR (α scan) yielded a highly skewed curve with a sharp change (sign-reversal) along with a rotational hysteresis around the a axis. Notably, at H < H c , the α-scan measurements on the single degenerate domain exhibited an anomalous sinusoidal signal of periodicity 360 • . Low-T evolution of the SMR curves (H = 2.4 kOe) suggests weakening of the anisotropy possibly due to the T evolution of Fe-R exchange coupling. Below 25 K, the SMR modulation showed an abrupt change around the c axis, marking the presence of a 2 phase. We have employed a simple Hamiltonian and computed SMR to examine the observed skewed SMR modulation. In summary, SMR is found to be an effective tool to probe magnetic anisotropy as well as a spin reorientation in Ho 0.5 Dy 0.5 FeO 3 . Our spin-transport study highlights the potential of Ho 0.5 Dy 0.5 FeO 3 for future AFM spintronic devices.

Nonzero Spontaneous Magnetic Moment along the b-Axis and the 2-Fold Spin Reorientation Transition in a Er0.4Gd0.6FeO3 Single Crystal

“…Rare-earth orthoferrites (RFeO 3 ) have a distorted perovskite structure with a space group of Pbnm . − As a functional material family, RFeO 3 attracts great scientific interest and has technological significance for potential applications such as magneto-optical switch, ultrafast optomagnetic recording, precession excitation induced by terahertz pulses, and magnetism-induced ferroelectric multiferroics. − Their abundant magnetic properties mainly originate from 3d-electrons of Fe 3+ and 4f-electrons of R 3+ . , The two magnetic ions (R 3+ and Fe 3+ ) form in three types of magnetic sublattices, including Fe 3+ –Fe 3+ , Fe 3+ –R 3+ , and R 3+ –R 3+ sublattices . The strongest one of those is Fe 3+ –Fe 3+ with G-type antiferromagnetic interaction, which causes the iron ions to orient opposite to all nearest neighbors in three dimensions below the first Neel temperature at 650–700 K. The presence of a Dzyaloshinskii–Moriya interaction − induces an asymmetric electronic exchange, resulting in a spontaneous magnetization in the c -axis of a RFeO 3 single crystal below the Neel temperature.…”