Spin polarization studies in half-metallic Co2TiX (X = Ge and Sn) Heusler alloys

In this paper, we investigated the Co2TiX (X = Ge, Sn) Heusler alloys by structural, magnetic and spin polarization measurements to probe the half-metallic nature. Alloys are synthesized using the arc melting technique, and found to exist in L21 crystal structure with Fm-3m space group. Curie temperature (TC) is found to be 384 and 371 K for Co2TiGe and Co2TiSn respectively. The saturation magnetization (MS) value of 1.8 and 2.0 Bohr magneton/f.u. are obtained at 5 K for for Co2TiGe and Co2TiSn respectively, compared to 2.0 Bohr magneton/f.u. calculated by Slater-Pauling rule. To obtain the spin polarization value, differential conductance curves are recorded at the ferromagnetic/superconducting point contact at 4.2 K. The current spin polarization (P) value of 0.63 and 0.64 are deduced for Co2TiGe and Co2TiSn respectively. Considering the high current spin polarization and TC, these materials appear to be promising for spintronic devices.