Anisotropic behavior of superconductivity in FeSe$_{\mathrm{0.5}}$Te$_{\mathrm{0.5}}$ thin films.

The resistive properties under angle-dependent magnetic fields up to 16 Tesla are investigated in superconducting FeTe$_{\mathrm{0.5}}$Se$_{\mathrm{0.5}}$ (FST) thin films grown on SrTiO$_{\mathrm{3}}$ (STO) substrates without or with a buffered CeO$_{\mathrm{2}}$ film. It is found that the FST/CeO$_{\mathrm{2}}$/STO films have an enhanced superconducting transition temperature and an induced superconducting anisotropy in comparison with the FST/STO films. These different behaviors in the absence and presence of the buffered CeO$_{\mathrm{2}}$ film are attributed to the change of the out-of-plane lattice constant, rather than the change of Se/Te heights within the tetrahedron.