Enhancement of Voltage-Controlled Magnetic Anisotropy in Orthogonally-Magnetized CoFeB/MgO/CoFeB

Voltage-controlled magnetic anisotropy (VCMA) is crucial for advancing high-speed, low-power magnetoresistive random-access memory (MRAM). Here, we report the optimization of the VCMA coefficient in an orthogonally-magnetized CoFeB/MgO(
$t$
)/CoFeB structure. By optimizing the MgO thickness, the VCMA value reaches
$\mathbf{53}\ \mathbf{fJ}/\mathbf{V}\cdot \mathbf{m}$
in the
$\boldsymbol{t}=\mathbf{2.6}$
nm sample, which has a 108.7% enhancement compared to the
$\boldsymbol{t}=\mathbf{2}$
nm counterpart. Moreover, by analyzing the MTJ capacitance with equivalent MTJ circuit model, we demonstrate that the improved VCMA coefficient is mainly attributed to the enlarged interfacial capacitance. Therefore, our work not only reveal the profound influence of barrier thickness on VCMA but also provide insights for the design of future VCMA-MRAM.