Energy efficient thermally induced magnetization switching by tailoring the electron and phonon dynamics

The recently discovered thermally induced magnetization switching [1] (TIMS) in ferrimagnets has received a lot of attention recently as it proceeds on the time-scale of picoseconds and occurs without the need for other slower additional external sources, such as a magnetic field. Whilst the energy per bit required to reverse the magnetization is low [2], the system temperature after the application of a pulse remains rather high for a few hundreds of picoseconds. In some cases the final temperature after the pulse is near the Curie temperature of the magnetic material. Moreover, the rate of heat transfer of energy out of the system is governed by phonon processes and can be reduced by careful selection of substrate, though the rate would still be of the order of hundreds of picoseconds. Thus, lowering the fluence required to reverse the magnetic state of a material by the TIMS mechanism is a key challenge since it could allow one to (i) realize an ultra-low power magnetic bit-recording scheme and (ii) avoid long lasting elevated temperatures. In considering the optimal set of physical characteristics we must first note that TIMS, whilst is a magnetic process [3], it relies strongly on the underlying physics of the electronic and phononic systems. The focus of this work is to address, at least partially, this issue by demonstrating the properties a candidate material that would give rise to a significant reduction of the laser power required to excite TIMS.