US Patent 12136446 TDMR SOT read heads having recessed topological insulator materials

The present disclosure generally relates to a two dimensional magnetic recording (TDMR) spin-orbit torque (SOT) read head comprising bismuth antimony (BiSb) layers. The read head comprises a lower reader comprising a first SOT stack and an upper reader comprising a second SOT stack. The first SOT stack and the second SOT stack each individually comprise a BiSb layer recessed from a media facing surface (MFS) and a free layer exposed at the MFS. The BiSb layers of each SOT stack are recessed from the MFS a distance of about 5 nm to about 20 nm, the distance being less than a length of the free layers. In one embodiment, the lower reader and the upper reader share a current path. In another embodiment, the lower reader and the upper reader have separate current paths.