Aberrant electronic and structural alterations in pressure tuned perovskite NaOsO3

Raimundas Sereika,Kazunari Yamaura,Peitao Liu,Sooran Kim,Bongjae Kim,Bijuan Chen,Jianbo Zhang,Changyong Park,Ho-Kwang Mao,Cesare Franchini,Yang Ding

doi:10.1038/s41535-020-00269-3

Abstract

The perovskite NaOsO3 has a metal–insulator transition at temperature 410 K, which is delicate, intriguing, and provokes a lot of debate on its nature. Our combined electrical resistance, Raman, and synchrotron x-ray diffraction experiments show that the insulating ground state in this osmate endures under high pressure up to at least 35 GPa. In this pressure range, compression reveals hidden hysteretic resistance properties with a transient metallic state near 200 K, manifested three electronic character anomalies (at 1.7, 9.0, and 25.5 GPa), and a structural transition to the singular polar phase (at ~18 GPa). We distinguish NaOsO3 from the regular crystallographic behavior of perovskites, though the electrical specificities resemble iridates and nickelates. The theoretical first-principle band structure and lattice dynamics calculations demonstrate that the magnetically itinerant Lifshitz-type mechanism with spin–orbit and spin–phonon interactions is responsible for these pressure-induced changes. Our findings provide another new playground for the emergence of new states in 5d materials by using high-pressure methods.

Highlights

The composition of NaOsO3 in the primitive cubic form has been known since 19741
The new orthorhombic phase attracted a lot of attention, because of its rare metal–insulator transition (MIT) which coincides with a long-range commensurate threedimensional antiferromagnetic (AFM) ordering at a rather high Néel temperature TN = TMIT = 410 K3–6
The G-type long-range commensurate AFM order occurs at the same temperature as the continuous MIT

Summary

INTRODUCTION

The composition of NaOsO3 in the primitive cubic form has been known since 19741. The orthorhombic perovskite NaOsO3 was only obtained in 20082,3. The anomalous spin-phonon behavior was linked to the extended 5d orbitals which relate to the magnetic structure through the Os–O–Os superexchange interactions In this regard, pressure becomes a favorable tool to induce many new features to emerge, because it can substantially affect the Fermi surface reconstruction[10,11] and, in turn, unpredictably vary the band gap. We discovered that, without increasing the temperature, the orthorhombic phase of NaOsO3 could transform into a polar perovskite phase with a space group of Pna[21], which violates the general trend of the perovskite oxides and has only been detected in PbRuO3 (Pbnm → Pbn21)[19] and LiOsO3 (R3c → R3c)[20] so far The latter two materials are nonmagnetic, while NaOsO3 has obvious magnetic properties[2,3,4,5,6,7,8,9] and preserves the band gap during the transition with a slow reduction of the MIT towards lower temperatures (T < 410 K). It is likely that this feature exists even at ambient pressure, because the resistivity in the BM regime does not show straight linear dependence on temperature (Supplementary Fig. 1) and, is naturally

RESULTS

DISCUSSION

METHODS