Liu Z Y, Dong Q X, Yang P T, Shan P F, Wang B S, Sun J P, Dun Z L, Uwatoko Y, Chen G F, Dong X L, Zhao Z X, Cheng J-G
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.
Phys Rev Lett. 2022 May 6;128(18):187001. doi: 10.1103/PhysRevLett.128.187001.
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 KMn_{6}Bi_{5}, which becomes the first ternary Mn-based superconductor. At ambient pressure, the quasi-one-dimensional KMn_{6}Bi_{5} is an antiferromagnetic metal with T_{N}≈75 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}≈13 GPa, around which bulk superconductivity emerges and displays a superconducting dome with the maximal T_{c}^{onset}=9.3 K achieved at about 14 GPa. The close proximity of superconductivity to a magnetic instability in the temperature-pressure phase diagram of KMn_{6}Bi_{5} and an unusually large μ_{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 AMn_{6}Bi_{5} (A=alkali metal) can open a new avenue for finding more Mn-based superconductors.
由于强烈的磁对破坏效应，锰基超导体十分罕见。在此，我们报告在KMn₆Bi₅中发现压力诱导超导性，它成为首个三元锰基超导体。在常压下，准一维KMn₆Bi₅是一种反铁磁金属，其奈尔温度Tₙ≈75 K。通过在立方砧室装置中测量高达14.2 GPa静水压力下的电阻和交流磁化率，我们发现其反铁磁转变在临界压力Pₑ≈13 GPa时可被完全抑制，在此压力附近出现体超导，并呈现出一个超导穹顶，在约14 GPa时实现最大超导起始温度Tₑⁱⁿˢᵉᵗ = 9.3 K。在KMn₆Bi₅的温度 - 压力相图中，超导与磁不稳定性的紧密接近以及异常大的μ₀Hₑ₂(0)超过泡利顺磁极限，表明存在一种非常规的磁介导配对机制。与二元MnP不同，三元AMn₆Bi₅（A =碱金属）中晶体结构和化学成分的灵活性可为寻找更多锰基超导体开辟新途径。
