Thermoelectric Spin-Transfer Torque MRAM with Sub-Nanosecond Bi-Directional Writing using Magnonic Current

TL;DR

This paper introduces a thermoelectric spin-transfer torque MRAM that uses magnonic currents controlled by temperature to achieve ultra-fast, energy-efficient, and reliable memory switching, surpassing conventional electric current methods.

Contribution

It proposes a novel thermoelectric approach for bi-directional writing in STT-MRAM using magnonic currents controlled by Peltier heating and cooling.

Findings

Reduces switching energy by over 40% compared to electric STT-MRAM.

Achieves sub-nanosecond precessional switching with low error rates.

Enhances device reliability and lifetime for non-volatile memory applications.

Abstract

A new genre of Spin-Transfer Torque (STT) MRAM is proposed, in which bi-directional writing is achieved using thermoelectrically controlled magnonic current as an alternative to conventional electric current. The device uses a magnetic tunnel junction (MTJ), which is adjacent to a non-magnetic metallic and a ferrite film. This film stack is heated or cooled by a Peltier element which creates a bi-directional magnonic pulse in the ferrite film. Conversion of magnons to spin current occurs at the ferrite-metal interface, and the resulting spin-transfer torque is used to achieve sub-nanosecond precessional switching of the ferromagnetic free layer in the MTJ. Compared to electric current driven STT-MRAM with perpendicular magnetic anisotropy (PMA), thermoelectric STT-MRAM reduces the overall magnetization switching energy by more than 40% for nano-second switching, combined with a write error rate (WER) of less than 10-9 and a lifetime of 10 years or higher. The combination of higher thermal activation energy, sub-nanosecond read/write speed, improved tunneling magneto-resistance (TMR) and tunnel barrier reliability make thermoelectric STT-MRAM a promising choice for future non-volatile memory applications.