Charge accumulation by Direct Magnetoelectric Effect in ScAlN/Ni Nanoscale Devices

TL;DR

This study demonstrates the direct magnetoelectric effect in nanoscale ScAlN/Ni heterostructures, showing charge accumulation and magnetic domain formation, with potential applications in miniaturized magnetic sensors and devices.

Contribution

It presents the first experimental evidence of charge accumulation via the direct magnetoelectric effect in nanoscale ScAlN/Ni heterostructures, combining fabrication, magnetic, and electrical characterization.

Findings

Charge accumulation up to 1.17 mV under magnetic fields.

Magnetic domains confirmed at sub-microscale.

Electrical integrity preserved at nanoscale.

Abstract

This work investigates the direct magnetoelectric effect in thin-film lab scale composite heterostructures comprising a 100 nm thick piezoelectric Sc0.4Al0.6N (ScAlN) and a magnetostrictive Ni with 100-200 nm thickness, fabricated on Si/SiO2 substrates. The films are patterned into square pillar arrays with lateral dimensions down to 500 nm x 500 nm. Vibrating sample magnetometry (VSM) measurements reveal in-plane magnetic anisotropy in the Ni films, attributed to strain induced by the underlying ScAlN layer. Nitrogen-vacancy (NV) magnetometry imaging confirms the formation of magnetic domains at remanence in polycrystalline Ni when patterned in sub-microscale structures. Capacitance measurements reveal a ScAlN dielectric constant at the device level consistent with unpatterned thin films, confirming the preservation of electrical integrity at the sub-microscale. The direct magnetoelectric effect is demonstrated through quasi-static charge measurements under applied out-of-plane DC magnetic fields, yielding equivalent open-circuit voltages up to 1.17 mV.