Spin-orbit torque induced electrical switching of antiferromagnetic MnN

Abstract

Electrical switching and readout of antiferromagnets allows to exploit the unique properties of antiferromagnetic materials in nanoscopic electronic devices. Here we report experiments on the spin-orbit torque induced electrical switching of a polycrystalline, metallic antiferromagnet with low anisotropy and high Néel temperature. We demonstrate the switching in a Ta / MnN / Pt trilayer system, deposited by (reactive) magnetron sputtering. The dependence of switching amplitude, efficiency, and relaxation are studied with respect to the MnN film thickness, sample temperature, and current density. Our findings are consistent with a thermal activation model and resemble to a large extent previous measurements on CuMnAs and Mn2Au, which exhibit similar switching characteristics due to an intrinsic spin-orbit torque.

Resistive contribution in electrical-switching experiments with antiferromagnets

“…Later, the Néel-order switching was also shown for Mn 2 Au films [3][4][5]. A greater variety of AFM can be switched using heterostructures that utilize the spin Hall effect (SHE) in an adjacent heavy metal (HM) like Pt to exert an antidamping torque on the Néel-order [6][7][8][9][10][11]. The reorientation can be realized with cross-shaped planar devices, where electrical pulses driven through the orthogonal lines allow for a reproducible switching of the Néelorder by 90 • .…”

Recent Developments on MnN for Spintronic Applications

“…The low anisotropy energy of MnN grains, especially at low thicknesses, can in some cases be seen as an advantage. The spin-orbit torque-induced electrical switching of polycrystalline MnN layers with the spin Hall effect of Pt has recently been studied [26]. The electrical manipulation of the magnetic order with current pulses was observed over a broad temperature range between 160 K and 260 K. With increasing temperature, a more efficient switching of the magnetic order was observed, with a simultaneous reduction in the relaxation time for randomization of the magnetic order.…”

First-principles calculations of spin-orbit torques in Mn$_2$Au/heavy-metal bilayers

“…Surprisingly, it was found using Hall resistance measurements that DL torque from the interface with Pt was strong enough to overcome the bulk FL torque in 10-nm and 25-nm Mn 2 Au(103) films, resulting in the reorientation of the AFM order parameter along the direction of the current [26]. Switching by DL torque has also been reported in other metallic antiferromagnets [27][28][29] that don't allow bulk torques.…”

“…A lot of research has focused on AFM/HM bilayers with insulating AFM [15,16,[18][19][20][21][22], but SOT-driven switching remains controversial, because the detection of AFM switching through magnetoresistance measurements is subject to artifacts of non-magnetic origin [23][24][25], while direct observations of magnetic switching can be explained by the thermomagnetoelastic mechanism that does not involve SOT [19,22]. Current-induced switching was also reported for a Mn 2 Au(103)/Pt bilayer [26] where the final state was different compared to a single layer of Mn 2 Au, and in other metallic AFM/HM bilayers [27][28][29].…”