  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.
