Multiple superconducting states induced by pressure in Mo3Sb7

Abstract

Tuning competing ordering mechanisms with hydrostatic pressure in the 4d intermetallic compound Mo3Sb7 reveals an intricate interplay of structure, magnetism, and superconductivity. Synchrotron x-ray diffraction and magnetic susceptibility measurements, both employing diamond anvil cell technologies, link a first-order structural phase transition to a doubling of the superconducting transition temperature. In contrast to the spin-dimer picture for Mo3Sb7, we deduce from x-ray absorption near-edge structure and dc magnetization measurements at ambient pressure that Mo3Sb7 should possess only very small, itinerant magnetic moments. The pressure evolution of the superconducting transition temperature strongly suggests its enhancement is due to a difference in the phonon density-of-states with changed crystal symmetry.