  In this work we investigated the temperature dependence of the upper critical
field u0Hc2(T) of Fe1.02(3)Te0.61(4)Se0.39(4) and Fe1.05(3)Te0.89(2)Se0.11(2)
single crystals by measuring the magnetotransport properties in stable dc
magnetic fields up to 35 T. Both crystals show that u0Hc2(T) in the ab-plane
and along the c-axis exhibit saturation at low temperatures. The anisotropy of
u0Hc2(T) decreases with decreasing temperature, becoming nearly isotropic when
the temperature T->0. Furthermore, u0Hc2(0) deviates from the conventional
Werthamer-Helfand-Hohenberg (WHH) theoretical prediction values for both field
directions. Our analysis indicates that the spin-paramagnetic pair-breaking
effect is responsible for the temperature-dependent behavior of u0Hc2(T) in
both field directions.
