under High Pressure Determined by Single Crystal X-ray Diffraction*

The 5d transition metal oxide NaOsO₃ attracts many attentions due to its metal-insulator transition, the origin of which is still under debate [1-3]. At ambient condition, NaOsO₃ crystallizes into an orthorhombic perovskite structure (Pbnm; a = 5.32817 Å, b = 5.38420 Å, c = 7.58038 Å). A high-pressure structural study was performed on polycrystalline NaOsO₃, which reported a highly unusual phase transition from nonpolar phase (Pbnm) to polar phase (Pna₂₁) at ~18 GPa [4]. Motivated by this report, we conducted the single-crystal synchrotron XRD measurement at high pressures up to 40 GPa and analyze the pressure effect on the crystal structure of NaOsO₃. Pressure enlarges the orthorhombic distortion, i.e. splitting the lattice parameters a, b, and c/, shown in figure 1. The single-crystal diffraction data of NaOsO₃ can be refined reasonably well with the Pbnm (No. 62) structural model up to ~40 GPa. In this talk, we will also compare the pressure effect on the orthorhombic perovskite NaOsO₃ with other 3d and 4d orthorhombic perovskite compounds.

[1] Y. G. Shi, Y. F. Guo, S. Yu, M. Arai, A. A. Belik, A. Sato, K. Yamaura, E. Takayama-Muromachi, H. F. Tian, H. X. Yang, J. Q. Li, T. Varga, J. F. Mitchell, and S. Okamoto, Continuous metal-insulator transition of the antiferromagnetic perovskite NaOsO₃, Phys. Rev. B. 80, 161104 (2009).

[2] S. Calder, V. O. Garlea, D. F. McMorrow, M. D. Lumsden, M. B. Stone, J. C. Lang, J. W. Kim, J. A. Schlueter, Y. G. Shi, K. Yamaura, Y. S. Sun, Y. Tsujimoto, and A. D. Christianson, Magnetically Driven Metal-Insulator Transition in NaOsO₃, Phys. Rev. Lett. 108, 257209 (2012).

[3] J. G. Vale, S. Calder, C. Donnerer, D. Pincini, Y. G. Shi, Y. Tsujimoto, K. Yamaura, M. M. Sala, J. van den Brink, A. D. Christianson, and D. F. McMorrow, Evolution of the Magnetic Excitations in NaOsO₃ through its Metal-Insulator Transition, Phys. Rev. Lett. 120, 227203 (2018).

[4] R. Sereika, P. Liu, B. Kim, S. Kim, J. Zhang, B. Chen, K. Yamaura, C. Park, C. Franchini, Y. Ding, and H.-k. Mao, Aberrant electronic and structural alterations in pressure tuned perovskite NaOsO₃, npj Quantum Mater. 5, 66 (2020).