Room temperature VCMA effect in SrTiO₃\Co\Pt trilayers and the impact of the interface

The standard material stacks with Perpendicular Magnetic Anisotropy (PMA) using MgO as a dielectric have an inherently limited Voltage Control of Magnetic Anisotropy (VCMA) effect^1,2. A higher permittivity of the gate dielectric increases the injected charge, likely enhancing the VCMA effect. The VCMA effect has recently been demonstrated on SrTiO₃(STO)\Co\Pt trilayers³: one condition is a minimal thickness of the magnetic dead layer (MDL) between STO and Co.

In this contribution, we apply different surface treatments to STO, before deposition of the Co thin film, to minimize the MDL thickness. The surface condition impacts the magnetic properties of the layers (studied with VSM), the crystalline structure (studied with TEM), the interdiffusion between the different layers (studied with EDS), the leakage current through STO, and the thickness of the MDL. We show a VCMA effect up to 12 fJ/Vm in samples treated with a surface sputtering. This report shows that the VCMA effect and the magnetic properties of STO\Co\Pt layers can be tailored with surface treatments and provides insights in the factors influencing the VCMA effect.

¹Maruyama, N Nano 4, 158 (2009)
²Kita, JAP 112, 033919 (2012)
³Vermeulen, submitted (2017)