Microwave study of FeSe0.3Te0.7 thin film by TE011-mode sapphire dielectric resonator

In this paper, we will report microwave study of FeSe_1-XTe_x (x=0.7) film by a sapphire dielectric cavity at 9.375 GHz. The resonator is a close analogy. The film was deposited on LaAlO₃ substrate and has Tc =11.8 K. The cavity, which has a Q-factor of 45000 in room temperature with TE₀₁₁-mode, is specially designed for the measurement of small samples with the sapphire cylinder having a small hole in the centre. The 100 nm thickness sample with dimension of 1-1.5 mm is put in the middle of the hole, supported by a very thin sapphire rod but isolated from the cylinder. The cavity is sealed in a vacuum chamber soaked in the liquid He and the temperature of the sapphire rod (hence the sample) can be controlled from 1.6 K to 60 K with a stability about ±1 mK while keeping the cavity remains in 4.2 K. Temperature dependence of resonance frequency and Q-factor of the resonator were measured by a vector network analyzer (Agilent N5230C) for both thin film and also the same substrate with no film on it.