Successive spatial symmetry breaking under high pressure in the spin-orbit-coupled metal Cd2Re2O7

Abstract

The 5d-transition metal pyrochlore oxide Cd2Re2O7, which was recently suggested to be a prototype of the spin-orbit-coupled metal [Phys. Rev. Lett. 115, 026401 (2015)], exhibits an inversion-symmetry breaking (ISB) transition at 200 K and a subsequent superconductivity below 1 K at ambient pressure. We study the crystal structure at high pressures up to 5 GPa by means of synchrotron X-ray powder diffraction. A rich structural phase diagram is obtained, which contains at least seven phases and is almost consistent with the electronic phase diagram determined by previous resistivity measurements. Interestingly, the ISB transition vanishes at ~4 GPa, where the enhancement of the upper critical field was observed in resistivity. Moreover, it is shown that the point groups at 8 K, probably kept in the superconducting phases, sequentially transform into piezoelectric, ferroelectric, and centrosymmetric structures on the application of pressure.

15 pages, 3 figures

References in corpus (4)

• Parity-breaking phases of spin-orbit-coupled metals with gyrotropic, ferroelectric and multipolar orders
• Tetrahedral Magnetic Order and the Metal-Insulator Transition in the Pyrochlore Lattice of Cd2Os2O7
• Metallic "Ferroelectricity" in the Pyrochlore Cd2Re2O7
• Goldstone-Mode Phonon Dynamics in the Pyrochlore Cd2Re2O7

Cited by in corpus (4)

• Pyrochlore Oxide Superconductor Cd2Re2O7 Revisited
• Crystal structure and the magnetic properties of the 5d transition metal oxide AOsO4 (A = K, Rb, Cs)
• Optical Hall response in spin-orbit coupled metals: Comparative study of magnetic cluster monopole, quadrupole, and toroidal orders
• High-pressure control of optical nonlinearity in the polar Weyl semimetal TaAs