Dielectric Capacitance – Voltage Response as a Predictor of Voltage-Controlled Magnetic Anisotropy Efficiency

Ion migration-based voltage-controlled magnetic anisotropy (VCMA) is a promising mechanism for energy-efficient spintronic devices. However, no established methods currently correlate dielectric properties with VCMA efficiency. Here, we demonstrate that VCMA efficiency can be predicted prior to full device implementation by detecting redox activity at the ferromagnet/oxide interface using conventional capacitance–voltage (C–V) measurements. We compare two HfO₂ with different chemical properties, one grown by thermal ALD (T-HfO₂) and the other by plasma-enhanced ALD (P-HfO₂), integrated as the gate dielectric on Ta/CoFeB/MgO/AlO_x structure. Results show that P-HfO₂ exhibits strong frequency dispersion and capacitance enhancement characteristic of redox-active electrochemical capacitors, along with significantly enhanced VCMA, whereas T-HfO₂ does not. These findings establish a direct correlation between dielectric C–V behavior and VCMA efficiency. We propose that standard C–V analysis can serve as a practical and predictive tool for evaluating and optimizing dielectric materials in VCMA-based spintronic applications.