Enhanced voltage-controlled magnetic anisotropy effect for low power spintronic applications

Abstract

With the advent of big-data era, low-power data storage & processing technology is required while the classical electronic devices reach its physical limitation. In this situation, scalable and low-power spintronic devices are getting attention. In particular, Voltage-controlled magnetic anisotropy (VCMA) has been actively studied as a future technology for low-power spintronic applications. This dissertation focuses on the development of enhanced VCMA system through various material engineering and its application. First, we introduce a thin platinum layer between the ferromagnetic/oxide interface for the large VCMA, allowing a magnetic easy-cone state to be formed and controlled by the gate voltage. As a result, the SOT switching current density is significantly reduced by modulating the magnetic easy-cone states through the VCMA. Furthermore, we demonstrate spintronic artificial synapses utilizing voltage-controlled magnetic multilevel states and energy- and area-efficient artificial neural network architectures associated with them. Second, we introduce $HfO_x$ gate oxide with the resistive switching for fast VCMA. The operation speed of VCMA is significantly reduced up to 20 ns. Additionally, the fast VCMA system exhibits excellent endurance. To show the feasibility of the fast VCMA, we integrate $HfO_x$ gate oxide into a spin logic device and improve the operation speed to nanosecond order.