Record-High Superconducting Transition Temperature in a TiMn Alloy with the Rich Magnetic Element Mn.

It is well-known that magnetic moments are very harmful to superconductivity. A typical example is the element Mn, whose compounds usually exhibit strong magnetism. Thus, it is very difficult to achieve superconductivity in materials containing Mn. Here, we report enhanced superconductivity with a superconducting transition temperature () up to a record-high value of about 26 K in a beta-phase TiMn alloy containing the rich magnetic element Mn under high pressures. This is contrary to the intuition that magnetic moments always suppress superconductivity. Under high pressures, we also found that in the middle-pressure regime, the Pauli limit of the upper critical field is surpassed. The synchrotron X-ray diffraction data show an unchanged beta-phase with a continuous contraction of the cell volume, which is well-supported by the first-principles calculations. Although the theoretical results based on electron-phonon coupling can interpret the value in a certain pressure region, the monotonic enhancement of superconductivity by pressure cannot seek support from the theory. Our results show a surprising enhancement of superconductivity in the TiMn alloy with a considerable Mn content.