Systematic Comparison of Eight Substrates in the Growth of FeSe$_{0.5}$Te$_{0.5}$ Superconducting Thin Films

摘要

We have investigated the crystal structures and superconducting properties ofthin films of FeSe$_{0.5}$Te$_{0.5}$ grown on eight different substrates.Superconductivity is not correlated with the lattice mismatch; rather it iscorrelated with the degree of in-plane orientation and with the latticeparameter ratio $c/a$. The best superconducting properties were observed infilms on MgO and LaAlO$_3$ ($T_\mathrm{c}^\mathrm{zero}$ of 9.5 K). TEMobservation showed that the presence or absence of an amorphous-like layer atthe substrate surface plays a key role in determining the structural andsuperconducting properties of the grown films.