Anomalous behavior of the quasi-one-dimensional quantum material Na${}_2$OsO${}_4$ at high pressure

Abstract

Na${}_2$OsO${}_4$ is an unusual quantum material that, in contrast to the common 5$d^2$ oxides with spins = 1, owns a magnetically silent ground state with spin = 0 and a band gap at Fermi level attributed to a distortion in the OsO${}_6$ octahedral sites. In this semiconductor, our low-temperature electrical transport measurements indicate an anomaly at 6.3 K with a power-law behavior inclining through the semiconductor-to-metal transition observed at 23 GPa. Even more peculiarly, we discover that before this transition, the material becomes more insulating instead of merely turning into a metal according to the conventional wisdom. To investigate the underlying mechanisms, we applied experimental and theoretical methods to examine the electronic and crystal structures comprehensively, and conclude that the enhanced insulating state at high pressure originates from the enlarged distortion of the OsO${}_6$. It is such a distortion that widens the band gap and decreases the electron occupancy in Os's $t_{2g}$ orbital through an interplay of the lattice, charge, and orbital in the material, which is responsible for the changes observed in our experiments.

arXiv commentManuscript with supplementary data, 24 pages

References in corpus (10)

• High-throughput electronic band structure calculations: challenges and tools
• One-Dimensional Fermi liquids
• Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CuO3
• Spin-Orbit Coupling in Iridium-Based 5d Compounds Probed by X-ray Absorption Spectroscopy
• Deconfinement transition and Luttinger to Fermi Liquid crossover in quasi one-dimensional systems
• Ba2NiOsO6: A Dirac-Mott insulator with ferromagnetism near 100 K
• Anomalous high-pressure Jahn-Teller behavior in CuWO4
• Effects of chemical pressure on the magnetic ground states of the osmate double perovskites SrCaCoOsO6 and Ca2CoOsO6
• Pressure control of conducting channels in singlewall nanotube networks
• Kondo physics in a Ni impurity embedded in O-doped Au chains