We report the $c$-axis resistivity measurements of ${\mathrm{FeTe}}_{0.6}{\mathrm{Se}}_{0.4}$ single-crystalline lamellae, extracted by using focused ion beam techniques, and determine the upper critical fields $H_{\mathrm{c}2}$ for $H\parallel c$ and $H\parallel ab$ down to 1.3 K. In contrast to early results based on the in-plane resistivity measurements, $H_{\mathrm{c}2}$ for $H\parallel c$ ($H_{\mathrm{c}2}^c$) shows a rapid increase just below the superconducting transition, at almost the same rate with that of $H_{\mathrm{c}2}$ for $H\parallel ab$ ($H_{\mathrm{c}2}^{ab}$). The whole temperature dependence of $H_{\mathrm{c}2}^c$ and $H_{\mathrm{c}2}^{ab}$ indicates that the Pauli pair-breaking effects become dominant for both $H_{\mathrm{c}2}^c$ and $H_{\mathrm{c}2}^{ab}$ of ${\mathrm{FeTe}}_{0.6}{\mathrm{Se}}_{0.4}$ where excess Fe is sufficiently removed. The quantitative comparison between the $c$-axis charge transport study in this work and the previous studies reveals that the magnetic pair-breaking mechanism is essentially independent of the current direction in the charge transport and that the details of $H_{\mathrm{c}2}\left(T\right)$ strongly depend on the excess Fe content.

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• Superconductivity
• Iron-based superconductors
• Focused ion beam
• Resistivity measurements