A new stable antiferromagnetic semiconductor: The case of inverse Heusler compound Ti2CrSn

The inverse Heusler compound Ti2CrSn with L21 phase is predicted to be antiferromagnetic semiconductor with an indirect gap of 0.2 eV based on first principles and Boltzmann transport theory. The semiconducting character is stable within a large strain from −6% to 6%. The Cr, Ti1 and Ti2 moments all show a linear change behavior within the strain range of −6%∼ 6%, however, the total zero moment is robust within that strain range. It should be a potential candidate for applying to magnetic tunnel junction device. The total zero moment originates from the fully occupied 9 orbitals for both up and down spin directions below the Fermi level. The spin dependent 3d hybridization feature is found that for up spin states the hybridization between Cr and Ti2 is dominant while for down spin states the hybridization between Ti1 and Ti2 is dominant, however, there is no clear indication of hybridization between Cr and Ti1. The gap origin of the spin up (down) direction is that the 3d hybridization of Cr−Ti2 (Ti1−Ti2) forms the bonding three degenerate t2g as well as two degenerate eg below the Fermi level, and also corresponding antibonding states of them above the Fermi level. This hybridization character also can be seen from the electron density difference that only the region between Cr and Ti2, and between Ti1 and Ti2 show clear electrons accumulation suggesting strong interaction. The calculated value of thermoelectric power factor is near to that of Bi2Te3, marking its potential application values in thermoelectric field.