Absence of superconductivity in the collapsed tetragonal phase ofKFe2As2under hydrostatic pressure

Temperature dependence of resistivity on $\mathrm{KF}{\mathrm{e}}₂\mathrm{A}{\mathrm{s}}₂$ single crystals down to 20 mK was measured under various hydrostatic pressures up to 17.5 GPa generated in a cubic-anvil cell. With increasing the pressure, the superconducting transition of tetragonal $\mathrm{KF}{\mathrm{e}}₂\mathrm{A}{\mathrm{s}}₂$ was suppressed gradually and disappears completely at \ensuremath{\sim}11 GPa, which was related to the weakening of electronic correlations and/or critical fluctuations under pressure. In sharp contrast to previous reports, no superconducting phase emerges upon further increasing pressures until the collapsed tetragonal $\mathrm{KF}{\mathrm{e}}₂\mathrm{A}{\mathrm{s}}₂$ forms. We argue that such a discrepancy can be attributed to the different pressure apparatus or homogeneity.