Observation of current-induced switching in non-collinear antiferromagnetic IrMn3 by differential voltage measurements

Abstract

There is accelerating interest in developing memory devices using antiferromagnetic (AFM) materials, motivated by the possibility for electrically controlling AFM order via spin-orbit torques, and its read-out via magnetoresistive effects. Recent studies have shown, however, that high current densities create non-magnetic contributions to resistive switching signals in AFM/heavy metal (AFM/HM) bilayers, complicating their interpretation. Here we introduce an experimental protocol to unambiguously distinguish current-induced magnetic and nonmagnetic switching signals in AFM/HM structures, and demonstrate it in IrMn3/Pt devices. A six-terminal double-cross device is constructed, with an IrMn3 pillar placed on one cross. The differential voltage is measured between the two crosses with and without IrMn3 after each switching attempt. For a wide range of current densities, reversible switching is observed only when write currents pass through the cross with the IrMn3 pillar, eliminating any possibility of non-magnetic switching artifacts. Micromagnetic simulations support our findings, indicating a complex domain-mediated switching process.

Antiferromagnetic Parametric Resonance Driven by Voltage-Controlled Magnetic Anisotropy

“…Figure 4 shows the Néel vector oscillation amplitude excited by SOT. Here, the ac electrical current is chosen large but achievable in experimentit is sufficiently small to prevent non-magnetic phenomena, such as electromigration [38], but is not far from this limit. The amplitude of Mode 1 is larger than the one of Mode 2 and is weakly dependent on the field in the studied range.…”

“…However, manipulation of AFM order is a more complex task than in ferromagnets due to the high exchange interaction, making it hard to manipulate them by magnetic fields. Recent experiments have demonstrated that the Néel vector dynamics can be driven by electrical currents via spin-orbit torque (SOT) effects [32][33][34][35][36][37][38]. This is especially important for the implementation of AFMs in hybrid CMOS/spintronic circuits.…”

Highly Tunable Magnetic and Magnetotransport Properties of Exchange Coupled Ferromagnet/Antiferromagnet-Based Heterostructures

“…In an AFM with two equivalent sublattice magnetizations denoted by M A and M B oriented antiparallel, | M A | = | M B | = M 0 is the magnitude of the sublattice magnetization; the normalized AFM Néel vector (order parameter) is given by l = ( M A – M B )/(2 M 0 ) . Electrical manipulation of the AFM Néel vector with the prospect of encoding information was achieved in various AFM compounds, such as CuMnAs, Mn 2 Au, Mn 3 Pt, , Mn 3 Sn, IrMn 3 , NiO, and CoO, via a relativistic mechanism, namely, Néel order spin–orbit torque (SOT)likely without invoking heat or magnetic fields. In strong contrast, recent experiments showed that significant amounts of charge current densities (≥4 × 10 7 A/cm 2 ) beyond the linear ohmic regime of the devices are needed to switch the Néel vector (or the local AFM domains). − The power efficiency, the physical mechanism of switching, and the efficiency of the electrical detection method for validating the current-induced microscopic switching of the AFM domains are currently under investigation. − Moreover, recent work based on NiO/Pt bilayer devices revealed a current-induced purely thermomagnetoelastic switching mechanism …”

“…5 In an AFM with two equivalent sublattice magnetizations denoted by M A and M B oriented antiparallel, |M A | = |M B | = M 0 is the magnitude of the sublattice magnetization; the normalized AFM Neél vector (order parameter) is given by l = (M A − M B )/(2M 0 ). 6 Electrical manipulation of the AFM Neél vector with the prospect of encoding information was achieved in various AFM compounds, such as CuMnAs, 2 Mn 2 Au, 7 Mn 3 Pt, 5,8 Mn 3 Sn, 9 IrMn 3 , 10 NiO, 11 and CoO, 12 via a relativistic mechanism, namely, Neél order spin−orbit torque 13 (SOT)likely without invoking heat or magnetic fields. In strong contrast, recent experiments showed that significant amounts of charge current densities (≥4 × 10 7 A/cm 2 ) beyond the linear ohmic regime of the devices are needed to switch the Neél vector (or the local AFM domains).…”

Time-dependent multistate switching of topological antiferromagnetic order in Mn$_3$Sn

“…Electric control of magnetic order in antiferromagnets has raised prospects for realizing high-speed and highdensity magnetoelectric devices using materials with zero net magnetization [1][2][3][4][5][6]. The switching of the order parameter in antiferromagnets is achieved by either injecting spin currents from an adjacent heavy metal layer or current-induced spin-orbit torques intrinsic to noncentrosymmetric crystals [7].…”