Probing magnetic anisotropy and spin-reorientation transition in 3D antiferromagnet, Ho${}_{0.5}$Dy${}_{0.5}$FeO${}_3|$Pt using spin Hall magnetoresistance

Abstract

Orthoferrites ($RE$FeO${}_3$) containing rare-earth ($RE$) elements are 3D antiferromagnets (AFM) 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 (HDFO$|$Pt) hybrid at various $T$ in the range, 11 to 300 K. In the room temperature ${\Gamma }_4(G_x,A_y,F_z)$ phase, the switching between two degenerate domains, ${\Gamma }_4(+G_x,+F_z)$ and ${\Gamma }_4(-G_x,-F_z)$ occurs at fields above a critical value, $H_{\text{c}}\approx 713$ Oe. Under $H>H_{\text{c}}$, the angular dependence of SMR ($\alpha$-scan) in the ${\Gamma }_4(G_x,A_y,F_z)$ phase yielded a highly skewed curve with a sharp change (sign-reversal) along with a rotational hysteresis around $a$-axis. This hysteresis decreases with an increase in $H$. Notably, at $H<H_{\text{c}}$, the $\alpha$-scan measurements on the single domain, ${\Gamma }_4(\pm G_x,\pm F_z)$ exhibited an anomalous sinusoidal signal of periodicity 360 deg. Low-$T$ SMR curves ($H$ = 2.4 kOe), showed a systematic narrowing of the hysteresis (down to 150 K) and a gradual reduction in the skewness (150 to 52 K), suggesting weakening of the anisotropy possibly due to the $T$-evolution of Fe-$RE$ exchange coupling. Below 25 K, the SMR modulation showed an abrupt change around the $c$-axis, marking the presence of ${\Gamma }_2(F_x,C_y,G_z)$ 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 HDFO. Our spin-transport study highlights the potential of HDFO for future AFM spintronic devices.

12 pages, 7 figures

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Cited by in corpus (1)

• Spin Quenching and Transport by Hidden Dzyaloshinskii-Moriya Interactions