Anomalous Charge State Evolution and Its Control of Superconductivity in M3Al2C (M = Mo, W)
Tianping Ying,
Yoshinori Muraba,
Soshi Iimura,
Tongxu Yu,
Peihong Cheng,
Toshio Kamiya,
Yangfan Lu,
Jiang Li,
Yanpeng Qi,
Hideo Hosono
Affiliations
Tianping Ying
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Yoshinori Muraba
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Soshi Iimura
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Tongxu Yu
State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200438, China; Laboratory of Advanced Materials, Fudan University, Shanghai 200438, China
Peihong Cheng
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
Toshio Kamiya
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Yangfan Lu
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Jiang Li
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan
Yanpeng Qi
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China; Corresponding author
Hideo Hosono
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503, Japan; Corresponding author
Summary: The charge states of elements dictate the behavior of electrons and phonons in a lattice, either directly or indirectly. Here, we report the discovery of an anomalous charge state evolution in the superconducting M3Al2C (M = Mo, W) system, where electron doping can be achieved through “oxidation.” Specifically, with the continuous removal of electron donor (Al) from the structure, we found an electron doping effect in the negatively charged transition metals. Over a certain threshold, the charge state of transition metals goes through a sudden reversion from negative to positive, which leads to a subsequent structure collapse. Concomitantly, the previous robust superconducting transition temperatures (Tcs) can be flexibly modulated. Detailed analysis reveals the origin of the superconductivity and the intimate relationship between the charge state and the electron-phonon coupling constant. The peculiar charge state in M3Al2C plays an important role in both its structure and superconductivity.
