Ionic Gel Modulation of RKKY Interactions in Synthetic Anti‐Ferromagnetic Nanostructures for Low Power Wearable Spintronic Devices

Abstract

To meet the demand of developing compatible and energy-efficient flexible spintronics, voltage manipulation of magnetism on soft substrates is in demand. Here, a voltage tunable flexible field-effect transistor structure by ionic gel (IG) gating in perpendicular synthetic anti-ferromagnetic nanostructure is demonstrated. As a result, the interlayer Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction can be tuned electrically at room temperature. With a circuit gating voltage, anti-ferromagnetic (AFM) ordering is enhanced or converted into an AFM-ferromagnetic (FM) intermediate state, accompanying with the dynamic domain switching. This IG gating process can be repeated stably at different curvatures, confirming an excellent mechanical property. The IG-induced modification of interlayer exchange coupling is related to the change of Fermi level aroused by the disturbance of itinerant electrons. The voltage modulation of RKKY interaction with excellent flexibility proposes an application potential for wearable spintronic devices with energy efficiency and ultralow operation voltage.

E‐field Control of the RKKY Interaction in FeCoB/Ru/FeCoB/PMN‐PT (011) Multiferroic Heterostructures

“…However, after changing the in‐plane vector, the BZ is also slightly distorted, which ends up to a reconfiguration of the Fermi surface. This strain‐mediated IEC modulation turns out to be a result of Fermi level tuning and has some consistency to our previous work . In this case, as represented in Figure e, with increasing the strain, the k || ‐resolved IEC break the C 6v symmetry, and found few region decrease (cold color), but more increase (warm color), which results that the integration of the k || ‐resolved IEC becomes larger and the AFM coupling fall weak.…”

“…The rapid growth of giant resistance (GMR) technology has inspired enormous research efforts for the RKKY interaction study in FM/NM/FM sandwich heterostructures . Significant progress has been achieved in the voltage controllable SAFs via ionic liquid/gel gating method . Nevertheless, this gating method suffers from a recovery problem because of the limited electrochemical reaction.…”

Ionitronic manipulation of current-induced domain wall motion in synthetic antiferromagnets

“…Here we show that, in a SAF structure, in which the lower and upper magnetic (LM and UM) layers are antiferromagnetically coupled via an ultrathin ruthenium layer 17,18 , gate voltages applied through ionic liquids can signi cantly affect the DW velocity with changes of several hundred m/s. We show that this is due to an electro-chemical process that is non-volatile but reversible and results from an enhancement or suppression of oxidation of the UM layer rather than from electrostatic changes in carrier density, as previously claimed [14][15][16]22,23 .…”

Flexible Antiferromagnetic FeRh Tapes as Memory Elements

“…[7][8][9] Most magnetic materials and devices have been engineered on polymeric substrates. For instance, embedded ferromagnetic elements, [10][11] anisotropic magnetoresistive, 12 GMR 13 and Hall effect sensors, 14 synthetic antiferromagnets (SAF), 9 magnetic tunneling devices 15 , or magnetoelectric devices [16][17][18][19] have been reported. In most of the cases, non-ordered magnetic metallic alloys were used because they allow close-to-room-temperature deposition as required by the polymeric substrates used.…”