# Enhancement of Thermal Spin Transfer Torque via Bandpass Energy Filtering

## TL;DR

This paper introduces a bandpass energy filtering method in magnetic tunnel junctions to significantly enhance thermal spin transfer torque, offering a more energy-efficient magnetization switching technique for spintronics.

## Contribution

The study demonstrates a novel anti-reflective coating-inspired heterostructure design that boosts thermal spin transfer torque by nearly five times using energy bandpass filtering.

## Key findings

- Thermally excited spin transfer torque is increased fivefold.
- Anti-reflective configuration enhances charge and spin transport.
- Technique offers an energy-efficient magnetization switching method.

## Abstract

We propose the use of energy bandpass filtering approach in the magnetic tunnel junction device as a route to enhance the thermal spin transfer torque. Using the spin-resolved non-equilibrium Green's function formalism, we harness the optical analog of anti-reflective coating in a heterostructure MTJ device, that reports a huge spin torque in the linear regime of temperature bias. In particular, we discuss the position of transmission function with respect to the Fermi energy that caters the maximum thermal effect. The boxcar transmission feature of anti-reflective configuration enhances the charge and spin transport through the structure in comparison to the normal superlattice configurations. The thermally excited spin transfer torque is enhanced by almost five times more with our device design. Although, the thermally driven spin torque is much smaller than the potential driven torque, this technique provides an energy-efficient way to switch the magnetization. This opens up a new viable area in the spintronics applications. With the existing advanced thin-film growth technology, the optimized superlattice configurations can be achieved.