Prediction of fully compensated ferrimagnetic and nonmagnetic semiconductors with promising thermoelectric properties through the Mo substitution of Cr for Ti2CrZ (Z=Ge, Sn) Heusler alloys

The electronic, magnetic and thermoelectric properties of Heusler alloys Ti2Cr1-x/4Mox/4Z (Z = Ge, Sn) (x = 1, 2, 3, 4) have been investigated by the density functional theory calculations and Boltzmann transport equation. The electronic band structures show that Ti2Cr1-x/4Mox/4Ge (x = 1, 2) and Ti2Cr1-x/4Mox/4Sn (x = 1, 2, 3) have the fully compensated ferrimagnetic semiconducting nature with totally zero magnetism, belonging to promising spintronic materials. The two full substitution alloys Ti2MoGe and Ti2MoSn belong to nonmagnetic semiconductors with both the atomic and total nonmagnetic moments. The total moment Mt of all the predicted semiconductors satisfy the rule of Mt = Zt-18 per unit cell since their valence electron numbers Zt are all 18, and the reason has been demonstrated according to the feature of fully occupied bands. Moreover, the three predicted semiconductors Ti2Cr1/2Mo1/2Ge, Ti2MoGe and Ti2MoSn have high thermoelectric power factor, indicating that they are the candidate thermoelectric materials for moderate temperature application.