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Voltage-driven strain-mediated modulation of exchange bias in Ir20Mn80/Fe80Ga20/Ta/⟨011⟩-oriented PMN-32PT heterostructures
24 May 2022
Manipulation of exchange bias with electric field is appealing to boost energy efficiency in spintronic devices. Here, this effect is shown at room temperature in Ir20Mn80/Fe80Ga20/Ta layers grown onto ⟨011⟩-oriented PMN-32PT single crystals. After magnetic field-cooling (FC) along the [01-1] and [100] in-plane directions of PMN-32PT and upon allowing the system to relax through consecutive hysteresis loops (training effect), the exchange bias field (HEB) is measured under the action of voltage (out-of-plane poling). Depending on the applied voltage (magnitude and sign), HEB can either increase or decrease with respect to its value at 0 V. The relative variations of HEB are 24% and 5.5% after FC along the [01-1] and [100] directions, respectively.

These results stem from strain-mediated magnetoelectric coupling. The applied electric field causes changes in the coercivity and the squareness ratio of the films, suggesting a reorientation of the effective magnetic easy axis in Fe80Ga20. However, larger HEB values are observed when the squareness ratio is lower. It is claimed that the effect of voltage is equivalent to an in-plane component of an applied magnetic field oriented perpendicular to the cooling field direction. Perpendicular in-plane magnetic fields have been shown to induce an increase in exchange bias in some ferromagnetic/antiferromagnetic systems due to partial recovery of the untrained antiferromagnetic state. Remarkably, here, this effect is directly induced with voltage, therefore enhancing energy efficiency.

This work was supported by TÜBİTAK (The Scientific and Technological Research Council of Turkey) through the Project No. 1059B192000016. Partial financial support by the European Research Council (MAGIC-SWITCH 2019-Proof of Concept Grant, Agreement No. 875018), the European Union's Horizon 2020 research and innovation programme (European Training Network, ETN/ITN Marie Skłodowska-Curie, Agreement No. 861145), the Spanish Government (Nos. Severo Ochoa FUNFUTURE-CEX2019-000917-SMCIN, AEI/10.13039/501100011033-, MAT2017-86357-C3-1-R, PID2019-107727RB-I00, PID2020-116844RB-C21, and PDC2021-121276-C31), the Generalitat de Catalunya (No. 2017-SGR-292), and the European Regional Development Fund (No. MAT2017-86357-C3-1-R) is acknowledged. E.M. is a Serra Húnter Fellow. A.Q. acknowledges the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva Formación Contract (No. FJC2019-039780-I).

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Oxides for new-generation electronics

Voltage-driven strain-mediated modulation of exchange bias in Ir20Mn80/Fe80Ga20/Ta/011⟩-oriented PMN-32PT heterostructures

E. Demirci, J. de Rojas, A. Quintana, I. Fina, E. Menéndez, and J. Sort

Appl. Phys. Lett. 120, 142406 (2022)