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fore another effect must compete with disorder. This may be the effect of excess Fe in Fe(2) position. 

Excess Fe in Fe(2) position is the unique feature of 11-system, different from other Fe pnictide superconduc- tors. The Fe(2) has larger local magnetic moment than Fe(1) in Fe-(Te,Se) layers. The Fe(2) moment is present even if the SDW antiferromagnetic ordering of the Fe plane is suppressed by doping or pressure, contributing to N ( E$_{F}$ ). 16 According to the expression of µ$_{0}$H$_{p}$ (0) with strong coupling correction considering e-boson and e-e interaction: 41 , 46 , 47 

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where η$_{Δ}$ describes the strong coupling intraband cor- rection for the gap, I is the Stoner factor I = N ( E$_{F}$ ) J , N ( E$_{F}$ ) is the electronic density of states (DOS) per spin at the Fermi level E$_{F}$ , J is an effective exchange integral, η$_{ib}$ is introduced to describe phenomenologically the ef- fect of the gap anisotropy, λ is electron – boson coupling constant and ε =0.5 or 1. It can be seen that µ$_{0}$H$_{p}$ (0) can decrease if the Stoner factor increases via enhance- ment of J or N ( E$_{F}$ ). Excess Fe in Fe(2) site with local magnetic moment could interact with itinerant electron in Fe layer, resulting in exchange enhanced Pauli para- magnetism or Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, thus enhancing J . Hence, higher content of excess Fe in Se-11, could lead to larger α$_{H}$$_{‖}$$_{c}$ than in Se-39. Another possibility may be that the N ( E$_{F}$ ) is de- creased with increasing the content of Se. 14 This trend will also enhance the Pauli limited field, i.e. suppress the spin-paramagnetic effect, according to above formula. This could be why the µ$_{0}$H$_{p}$ (0) of Se-39 is higher than that of Se-11 if we assume other parameters in eq. (6) are not changed. 

Finally, we discuss the anisotropy of µ$_{0}$H$_{c}$$_{2}$ ( T ). The temperature dependence of anisotropy of µ$_{0}$H$_{c}$$_{2}$ ( T ), γ (= H$_{c}$$_{2}$$_{,ab}$ ( T ) /H$_{c}$$_{2}$$_{,c}$ ( T )), obtained from the µ$_{0}$H$_{c}$$_{2}$$_{,onset}$ ( T ) data is shown in Fig. 6(c) as a function of reduced temperature t = T/T$_{c}$ . The γ of Se-11 is smaller than that of Se-39. The difference in γ between the two samples decreases gradually. Both γ values decrease to about 1 with decreasing temperature, larger than in Fe(Te,S) and similar to previously reported in Fe(Te,Se). 27 , 43 These results show that Fe(Te,Se) is a high-field isotropic superconductor. 

In summary, the anisotropy in the upper critical field of Fe$_{1}$$_{.}$$_{02(3)}$Te$_{0}$$_{.}$$_{61(4)}$Se$_{0}$$_{.}$$_{39(4)}$ and Fe$_{1}$$_{.}$$_{05(3)}$Te$_{0}$$_{.}$$_{89(2)}$Se$_{0}$$_{.}$$_{11(2)}$ single crystals was studied in high and stable magnetic fields up to 35 T. It is found that the zero-temperature upper critical field is much smaller than the predicted result of WHH theory without the spin-paramagnetic ef- fect. The anisotropy of the upper critical field decreases with decreasing temperature, becoming nearly isotropic at low temperature. The spin-paramagnetic effect is the dominant pair-breaking mechanism for both of H ‖ ab and H ‖ c. 

## V. CONCLUSION 

