At the edge of physics – how do we search new materials

Sepeaker: Prof. Tomasz Klimczuk
Affiliation: Gdańsk University of Technology, Institute of Nanotechnology and Material Engineering, Gdańsk, Poland
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In the lecture, I will present strategies for searching for new materials whose physical properties may be of interest to solid state physicists. I will give details of the projects that have led to the discovery of new superconducting compounds. The success of the projects was possible thanks to the symbiosis between physicists, chemists and crystallographers. In particular, I will discuss recently reported the Heusler-type superconductors: MgPd2Sb [1], LiPd2Ge [2], LiGa2Rh [3] and LiGa2Ir [4].

MgPd2Sb is the first Mg-based a Heusler-type compound in which superconductivity is revealed. The number of valence electrons for MgPd2Sb is VEC = 27 and falls exactly at the maximum of the proposed Tc vs. VEC [5]. For LiPd2Ge the number of valence electrons is 2 lower, while for the other two Li-based superconductors (LiGa2Rh and LiGa2Ir) VEC = 16. While the last two materials are type-II superconductors, LiPd2Ge is a rare case of an intermetallic compound for which type-I superconductivity is observed. Theoretical calculations of the phonon structure indicate the possibility of the so-called soft modes in LiPd2Ge, which lead to the amplification of the electron-phonon coupling and consequently to the occurrence of superconductivity in this family.

This project is supported by the two National Science Centre (Poland) projects: 2017/27/B/ST5/03044 (PG) and 2017/26/E/ST3/00119 (AGH).

[1] M.J. Winiarski, et al., Phys. Rev. B, 103, 214501 (2021).
[2] K. Górnicka, et al., Phys. Rev. B, 102, 024507 (2020).
[3] E. Carnicom, et al., Sci. Adv. 2018, 4, eaar7969 (2018).
[4] K. Górnicka, et al., Scientific Reports, 11, 16517 (2021).
[5] T. Klimczuk, et al., Phys. Rev. B, 85, 174505 (2012).

Chairman: Prof. Sławomir Breiter