An all-Heusler magnetic tunnel junction model which provides a probability to realize maximal tunneling magnetoresistance at room temperature

The CoFeTiSi compound is an experimentally existing half-metallic ferromagnetic Heusler compound with a Curie temperature higher than room temperature. By replacing the Si atom with Al, we can obtain a narrow bandgap semiconductor CoFeTiAl. The lattice mismatch between CoFeTiSi and CoFeTiAl is very small, which serves as motivation for constructing a CoFeTiSi/CoFeTiAl/CoFeTiSi magnetic tunnel junction. In this junction, CoFeTiSi and CoFeTiAl are used as electrode and barrier layers, respectively. The optimal device structure can be achieved simply by replacing the Si atoms in the barrier region with Al atoms. Through the use of ab initio atomic thermodynamics, we have found that this device structure is more stable compared to a junction formed by the same two compounds with an alternative interface. Transport calculations reveal that this junction can achieve a high tunneling magnetoresistance ratio at room temperature and exhibit a large transmission coefficient. These characteristics make the CoFeTiSi/CoFeTiAl/CoFeTiSi magnetic tunnel junction an ideal candidate for future spintronic applications.