Evidence of superconductivity in amorphous TiNiSn thin films

J. BARZOLA-QUIQUIA; OSMIC, E.; P. G. BERCOFF; L. VENOSTA; P. HAUSSLER

Encuentro; XXI Encuentro de Superficies y Materiales Nanoestructurados (NANO 2022); 2022

We have investigated the resistance temperature dependence R(T) of the amorphous TiNiSn alloy, in the temperature range 1.2 K to 345 K. After preparation by quenching at T≈4.2 K, R(T) was measured in-situ during and after annealing at 345 K. This measurements show that the sample is superconducting and Tc increases with annealing. Electron diffraction after annealing at T=345 K, shows the sample is in a pure amorphous phase, with a well-defined local spherical periodic order. After a heat treatment at T=850 K, the amorphous TiNiSn structure crystallizes at TK≈785 K. Analysis of the crystallized sample indicates that a well-ordered half-Heusler crystalline phase is obtained, with TiNiSn atoms position in the unit cell and not the NiTiSn ordering, as usual. We attribute this results to the preparation method and the low annealing temperature after crystallization.