Tripling the critical temperature of KFe${}_2$As${}_2$ by carrier switch

Abstract

Superconductivity of high critical temperature ($T_c$) superconductors is usually realized through chemical dopant or application of pressure in a similar way to induce charge carriers of either electrons or holes into their parent compounds. For chemical doping, superconductivity behaves asymmetrically with the maximum $T_c$ often higher for optimal hole-doping than that of optimal electron-doping on the same parent compound. However, whether electron carriers could be in favour of higher $T_c$ than holes in such high-$T_c$ superconductors is unknown but attractive. Here we show that the application of pressure can drive KFe${}_2$As${}_2$ from hole- to electron-superconductivity after passing the previously reported $V$-shape or oscillation regime. The maximum $T_c$ in the electron-dominated region is tripled to the initial value of 3.5 K or the average in the low-pressure hole-dominated region. The structural transition takes place from the tetragonal to collapsed tetragonal phase when the carrier characteristic is changed upon compression. Our results unambiguously offer a new route to further improve superconductivity with huge $T_c$ enhancement for a compound through carrier switch. The strong electronic correlations in KFe${}_2$As${}_2$ are suggested to account for the unexpected enhancement of superconductivity in the collapsed tetragonal phase.

arXiv comment20 pages, 6 figures

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Cited by in corpus (8)

• Pressure induced half-collapsed-tetragonal phase in CaKFe${}_4$As${}_4$
• Quantum criticality in AFe2As2 with A = K, Rb, and Cs suppresses superconductivity
• Unconventional superconductivity in the layered iron germanide YFe${}_2$Ge${}_2$
• Origin of the superconducting state in the collapsed tetragonal phase of KFe2As2
• Ab-initio perspective on structural and electronic properties of iron-based superconductors
• Non-trivial role of interlayer cation states in iron-based superconductors
• Structural, electronic, and dynamical properties of the tetragonal and collapsed tetragonal phases of KFe${}_2$As${}_2$
• Nearly ferromagnetic metal state in the collapsed tetragonal phase of YFe${}_2$(Ge,Si)${}_2$