Inverse-magnetostriction-induced switching current reduction of STT-MTJs and its application for low-voltage MRAM

A new spin-transfer torque (STT) magnetic tunnel junction (MTJ) using an inverse magnetostriction (IMS) material for the free layer is proposed for low-voltage MRAMs. The MTJ is surrounded by a piezoelectric gate structure so that a pressure for introducing the IMS effect can efficiently be applied to the free layer without any high-yield-strength support structure. During STT-induced magnetization switching, the energy barrier height for the switching can be lowered by the IMS effect, and thus a critical current density (JC) for the magnetization switching can dramatically be reduced. Energy performance of a low-voltage STT-MRAM cell using the proposed MTJ and a FinFET is also demonstrated.