Pressure-Induced Superconductivity up to 9 K in the Quasi-One-Dimensional <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>KMn</mml:mi></mml:mrow><mml:mn>6</mml:mn></mml:msub><mml:msub><mml:mi>Bi</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math>
Ziyi Liu, Qingxin Dong, Pengtao Yang, Pengfei Shan, Bosen Wang, Jianping Sun, Zhiling Dun, Yoshiya Uwatoko, Genfu Chen, Xiaoli Dong, Zhongxian Zhao, Jinguang Cheng
Abstract
The Mn-based superconductor is rare owing to the strong magnetic pair-breaking effect. Here we report on the discovery of pressure-induced superconductivity in ${\mathrm{KMn}}_{6}{\mathrm{Bi}}_{5}$, which becomes the first ternary Mn-based superconductor. At ambient pressure, the quasi-one-dimensional ${\mathrm{KMn}}_{6}{\mathrm{Bi}}_{5}$ is an antiferromagnetic metal with ${T}_{N}\ensuremath{\approx}75\text{ }\text{ }\mathrm{K}$. By measuring resistance and ac magnetic susceptibility under hydrostatic pressures up to 14.2 GPa in a cubic anvil cell apparatus, we find that its antiferromagnetic transition can be suppressed completely at a critical pressure of ${P}_{c}\ensuremath{\approx}13\text{ }\text{ }\mathrm{GPa}$, around which bulk superconductivity emerges and displays a superconducting dome with the maximal ${T}_{c}^{\text{onset}}=9.3\text{ }\text{ }\mathrm{K}$ achieved at about 14 GPa. The close proximity of superconductivity to a magnetic instability in the temperature-pressure phase diagram of ${\mathrm{KMn}}_{6}{\mathrm{Bi}}_{5}$ and an unusually large ${\ensuremath{\mu}}_{0}{H}_{c2}(0)$ exceeding the Pauli paramagnetic limit suggests an unconventional magnetism-mediated paring mechanism. In contrast to the binary MnP, the flexibility of the crystal structure and chemical compositions in the ternary $A{\mathrm{Mn}}_{6}{\mathrm{Bi}}_{5}$ ($A=\text{alkali}$ metal) can open a new avenue for finding more Mn-based superconductors.