Pauli-limited effect in the magnetic phase diagram of FeSexTe1−x thin films

We present a detailed investigation on the doping dependence of the upper critical fieldHc2(T) of FeSexTe1−xthin films (0.18 ≤ x ≤ 0.90) by measuring the electrical resistivity as a function of magnetic field. The Hc2(T) curves exhibit a downturn behavior with decreasing temperature in all the samples, owing to the Pauli-limited effect (spin paramagnetic effect). The Pauli-limited effect on the upper critical field can be monotonically modulated by variation of the Se/Te composition. Our results show that Te-doping induced disorder and excess Fe atoms give rise to enhancement of the Pauli-limited effect.