Voltage polarity-dependent anomalous Hall effect modulation in Fe5GeTe2 via ion gel gating

Energy-efficient electric-field control of magnetism is critical for low-power spintronic devices and next-generation magnetic storage. Herein, we systematically investigate the anomalous Hall effect in the itinerant van der Waals (vdW) ferromagnet Fe5GeTe2 modulated by an 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ion gel gate. Magnetotransport measurements reveal a giant, polarity-dependent modulation: a positive gate bias induces a ∼312% enhancement in the ordinary Hall coefficient (R0) and a ∼195% increase in the anomalous Hall coefficient (RS) at 200 K, whereas negative bias results in a modest change (<30%). Thickness-dependent studies demonstrate that the gating effect is confined to surface layers, excluding bulk ion intercalation effect. The irreversible, non-volatile modulation behavior—supported by steady gate leakage current—suggests a synergistic mechanism where proposed interfacial electrochemical reactions coexist with electrostatic effects, collectively driving the giant and non-volatile transport response. Our findings clarify the gating mechanism of large organic ions in two-dimensional vdW magnets and establish a robust pathway toward non-volatile Write-Once-Read-Many spintronic memory devices.