Superconductivity of platinum hydride PtH*

Pt has a strong electron-phonon (e-p) coupling [1]. On the other hand, the 5d conduction electrons show strong spin fluctuations on the short length and time scales, which suppress the superconductivity. In PtH, hybridization between Pt 5d and H 1s [2] and the resulting strengthened e-p coupling and T_c above 10 K have been predicted [2-5]. We report the ac magnetic susceptibility, electrical resistance, and x-ray diffraction measurements of PtH in diamond anvil cells. At 30 GPa, when PtH is in a P6₃/mmc structure, PtH exhibits the superconducting transition at 7 K. The observed T_c is higher than that of powdered Pt by more than three orders of magnitude. It is suggested that the noble metal hydrides possibly have higher T_c than elements.
[1] Albert and Rubin, in Platinum Group Metals and Compounds, (American Chemical Society, Washington, 1971), Chap. 1, pp. 1-16. [2] Papaconstantopoulos, J. Less-Common Met. 73, 305 (1980). [3] Scheler et al., Phys. Rev. B 83, 214106 (2011). [4] Kim et al., Phys. Rev. Lett. 107, 117002 (2011). [5] Zhou et al., Phys. Rev. B 84, 054543 (2011).