Ultrafast and low-energy switching in voltage-controlled elliptical pMTJ

Abstract

Switching magnetization in a perpendicular magnetic tunnel junction (pMTJ) via voltage controlled magnetic anisotropy (VCMA) has shown the potential to markedly reduce switching energy. However, the requirement of an external magnetic field poses a critical bottleneck for its practical applications. In this work, we propose an elliptical-shaped pMTJ to eliminate the requirement of providing an external field by an additional circuit. We demonstrate that a 10 nm thick in-plane magnetized bias layer (BL) separated by a metallic spacer of 3 nm from the free layer (FL) can be engineered within the MTJ stack to provide the 50 mT bias magnetic field for switching. By conducting macrospin simulation, we find that a fast switching in 0.38 ns with energy consumption as low as 0.3 fJ at a voltage of 1.6 V can be achieved. Furthermore, we study the phase diagram of switching probability, showing that a pulse duration margin of 0.15 ns is obtained and low-voltage operation (~1 V) is favored. Finally, the MTJ scalability is considered, and it is found that scaling down may not be appealing in terms of both the energy consumption and the switching time for precession based VCMA switching.

Route Towards Efficient Magnetization Reversal Driven by Voltage Control of Magnetic Anisotropy

“…So far in literature, the diagrams reported are similar to those in Fig. 2(c) since the ratio between Hip and HK is large [19] [28] [34]. Fig.…”

“…Many first principle studies have been dedicated to this topic, generally for systems composed of a heavy metal, a 3d ferromagnet and a dielectric, typically MgO [15] [16] [17] [18]. Simultaneously, experimental evidence of voltage controlled magnetic anisotropy (VCMA) has emerged in a wide range of structures, and static and dynamic measurements have been performed in order to explore its limits [19]. However, from the micromagnetic and macrospin simulations point of view, this field is not explored enough and a deep understanding of the behavior of magnetization in this framework and of its governing parameters is still needed.…”

“…Some studies on VCMA using the micromagnetic framework aim at explaining the magnetization reversal process under the influence of an electric field, with some design approaches being proposed [20] [21] [22]. A broad variety of macrospin studies exist, oriented towards the optimization of system operation through pulse shape [23] [24], thermal stability [25] and towards decreasing of the write-error-rate (WER), some of which accompanied by experimental studies [19] [25]. Other macrospin studies focus on the association between VCMA and spin transfer torque (STT) methods of magnetization manipulation [28] or on the VCMA and a Rashba field which is used as an in-plane bias magnetic field [26].…”

From MTJ Device to Hybrid CMOS/MTJ Circuits: A Review

“…It modifies the spin-orbit interaction at the interface and changes the MA. The reduced MA enables the capability of magnetization switching of MTJ with low power dissipation [151]. It motivated the researcher to develop hybrid circuits [152,153] and NV memory [154,155] using this mechanism.…”

Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy

“…Many first principle studies have been dedicated to this topic, generally for systems composed of a heavy metal, a 3 d ferromagnet and a dielectric, typically MgO 14 – 17 . Simultaneously, experimental evidence of voltage controlled magnetic anisotropy (VCMA) has emerged in a wide range of structures, and static and dynamic measurements have been performed in order to explore its limits 18 . However, from the micromagnetic and macrospin simulations point of view, this field is not explored enough and a deep understanding of the behavior of magnetization in this framework and of its governing parameters is still needed.…”