Antiferromagnet-controlled spin current transport in ${\mathrm{SrMnO}}_3/\mathrm{Pt}$ hybrids

We investigate the spin Hall magnetoresistance (SMR) in $\mathrm{SrMn}{\mathrm{O}}_3\left(\mathrm{SMO}\right)/\mathrm{Pt}$ hybrids, where SMO is an antiferromagnetic (AFM) insulator. The AFM moments partially rotate with out-of-plane magnetic fields, producing room-temperature SMR. By manipulating the electron spins in Pt, we observe Larmor precession-induced oscillating SMR, reaffirming the spin current transport determined by the relative arrangement between the Pt electron spins and AFM moments. The use of the AFM with no net moments annihilates the magnetic proximity effect and thus confirms the SMR origination from AFM-controlled spin current transport, with significant spin mixing conductance of $\sim {10}^{17}{\mathrm{m}}^{-2}$. Our findings provide an interesting perspective to detecting AFM moments and represent a significant step towards AFM spintroincs.

Figure 1

(a) The AFM moment arrangement in the (001) plane of SMO. (b) A schematic of the sample layout. (c) Low resistance state at the zero field or with in-plane $H$. (d) High-resistance state with out-of-plane $H$. The SMR is determined by the interfacial relative arrangement between the electron spins $\left(\mathit{s}\right)$ in Pt and the AFM moments $\left(\mathit{m}\right)$ in SMO.

Figure 2

(a) and (b) Resistance curves of SMO/Pt (7 nm) and SMO/Pt (3 nm) when sweeping an out-of-plane $H$ at room temperature. (c) Resistance curve of SMO/Pt (7 nm) when sweeping an in-plane $H$ at room temperature. (d) Resistance curves of SMO/Pt (7 nm) when sweeping out-of-plane and in-plane $H$ at 10 K after out-of-plane and in-plane field-cooling treatments, respectively.

Figure 3

(a)–(c) $\alpha$, $\beta$, and $\gamma$ dependence of the resistance in SMO/Pt (7 nm), where $\alpha$, $\beta$, and $\gamma$ are defined in the schematics related to each resistance curve. The $\alpha$, $\beta$, and $\gamma$ curves are all measured under the $H$ of 1, 5, and 9 T, respectively. (d) The dependence of the Pt resistance in YIG/Pt (7 nm) on $\alpha$, $\beta$, and $\gamma$ when rotating a magnetic field of 100 mT. All the data were recorded at 300 K.

Figure 4

Oscillating resistance signals induced by the Larmor precession in the Pt layer for (a) SMO/Pt (7 nm) and (c) YIG/Pt (7 nm) bilayers when sweeping a small out-of-plane magnetic field at 300 K. The magnetic field starts from 0 to 50 mT in small steps (∼0.5 mT). Corresponding schematics of the Larmor precession in SMO/Pt and YIG/Pt bilayers are shown in (b) and (d), respectively.