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

AbstractThere 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.

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Theoretical Study of Field-Free Switching in PMA-MTJ Using Combined Injection of STT and SOT Currents

Micromachines ◽

10.3390/mi12111345 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1345

Author(s):

Shaik Wasef ◽

Hossein Fariborzi

Keyword(s):

Critical Current ◽

Theoretical Study ◽

Tunnel Junctions ◽

Spin Transfer Torque ◽

Spin Transfer ◽

Spin Orbit ◽

Micromagnetic Simulations ◽

Spintronic Devices ◽

Current Densities ◽

The Relationship

Field-free switching in perpendicular magnetic tunnel junctions (P-MTJs) can be achieved by combined injection of spin-transfer torque (STT) and spin-orbit torque (SOT) currents. In this paper, we derived the relationship between the STT and SOT critical current densities under combined injection. We included the damping–like torque (DLT) and field-like torque (FLT) components of both the STT and SOT. The results were derived when the ratio of the FLT to the DLT component of the SOT was positive. We observed that the relationship between the critical SOT and STT current densities depended on the damping constant and the magnitude of the FLT component of the STT and the SOT current. We also noted that, unlike the FLT component of SOT, the magnitude and sign of the FLT component of STT did not have a significant effect on the STT and SOT current densities required for switching. The derived results agreed well with micromagnetic simulations. The results of this work can serve as a guideline to model and develop spintronic devices using a combined injection of STT and SOT currents.

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STUDIES ON THE ELECTRO-OXIDATION OF TETRAVALENT URANIUM

Canadian Journal of Research ◽

10.1139/cjr48b-044 ◽

1948 ◽

Vol 26b (5) ◽

pp. 441-455

Author(s):

R. H. Betts

Keyword(s):

Aqueous Solution ◽

Uranyl Ion ◽

Ion Concentration ◽

Anode Potential ◽

High Current ◽

Tetravalent Uranium ◽

Platinum Anode ◽

Wide Range ◽

Current Densities ◽

Electro Oxidation

The conversion of uranous ion to uranyl ion at a platinum anode has been studied over a wide range of current densities and anode potentials. At high current densities, the rate of the oxidation is dependent on the uranous ion concentration and is independent of the particular current density used. At low current densities, the rate of the process increases exponentially with increases in the anode potential and temperature, but is independent of the uranyl ion concentration. It is concluded that at high current densities, the rate of oxidation is limited by the rate of diffusion of uranous ion to the anode, while at low current densities, the rate of the reaction is limited by the slowness in electron transfer between the metallic ion and the anode. A formal correlation is made between the irreversible characteristics of this system and those displayed during the electrodeposition of hydrogen and oxygen from aqueous solution.

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General considerations on the theory of the separation of H 1 and H 2 by electrolysis of water

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1934.0060 ◽

1934 ◽

Vol 144 (852) ◽

pp. 452-466 ◽

Cited By ~ 6

Keyword(s):

A Priori ◽

Point Of View ◽

Theoretical Point ◽

High Current ◽

Hydrogen Electrode ◽

Effective Separation ◽

A Value ◽

Rates Of Evolution ◽

Wide Range ◽

Current Densities

1. The Facts .―In a solution of NaOH (or KOH) with nickel (perhaps with other) electrodes and at high current densities of the order of 1 ampere per cm. 2 of electrode the observed rates of evolution E 1 and E 2 of H 1 and H 2 at the cathode obey an equation of the type E 1 /E 2 = q D 1 /D 2 , (1) where D 1 and D 2 are the relative concentraction of the H 1 and H 2 atoms in the water as a whole. The coefficient q has been shown to be independent of D 1 /D 2 over a very wide range of relative concentrations. Under the conditions most favourable to separation, which appear to be those just specified, q can have a value as great as 6, or perhaps 7. With other metals than nickel for the electrodes and with lower current densities the factor q may fall to a value well below 2 or even to a value so nearly unity that no effective separation occurs. The dependence of q (if any) on the temperature of the solution is not known. 1.1. The Arguments .―The facts have already been commented on by Polanyi from the theoretical point of view. He has been led to conclude from them that the separation is to be attributed to a difference of " over potential" for the deposition of H 1 and H 2 ions on the cathode, and consequently that Gurney's theory of the over-potential of the hydrogen-electrode at low current densities (as measured, for example, by Bowden) must be discarded. These conclusions if correct and unavoidable are of the greatest importance. It is most general way possible, in order to see that no types of mechanism have been overlooked which could lead to the observed results. When this is done it is found that the mechanism discussed by Polanyi which refers the separation to differences of over-potential is not the only mechanism which must be held possible a priori . The observed separation could perfectly well occur by a mechanism consistent with Gurney's theory. It does not yet appear to be possible to decide confidently between the two possibilities on experimental grounds.

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