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

• Co2TiX (X = Ge, Sn) alloys were synthesized by using the arc melting technique.
• High value of Curie temperature was obtained for both alloys.
• High value of current spin polarization (P) was deduced for both the alloys.
• Deduced P is higher than those obtained for many ternary and/or quaternary alloys.
• These materials are quite promising for the spintronic devices.

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 were 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 μB/f.u. are obtained at 5 K for Co2TiGe and Co2TiSn respectively, compared to 2.0 μB/f.u. calculated by Slater-Pauling rule. To obtain the spin polarization value, differential conductance curves were recorded at the ferromagnetic/superconducting point contact at 4.2 K. The current spin polarization (P) value of 0.63 ± 0.03 and 0.64 ± 0.02 were deduced for Co2TiGe and Co2TiSn respectively. Considering the high current spin polarization and TC, these materials appear to be promising for spintronic devices.