Pressure induced second-order structural transition in Sr₃Ir₂O₇

Abstract

We conducted in situ angle dispersive high pressure x-ray diffraction experiments on Sr3Ir2O7 up to 23.1 GPa at 25 K with neon as the pressure transmitting medium. Pressure induces a highly anisotropic compressional behavior seen where the tetragonal plane is compressed much faster than the perpendicular direction. By analyzing different aspects of the diffraction data, a second-order structural transition is observed at approximately 14 GPa, which is accompanied by the insulating state to nearly metallic state at 13.2 GPa observed previously (Li et al 2013 Phys. Rev. B 87 235127). Our results highlight the coupling between electronic state and lattice structure in Sr3Ir2O7 under pressure.

Pressure dependence of the structure and electronic properties ofSr3Ir2O7

“…Rietveld refinement suggests that the stacking sequence of the two perovskite bilayers is altered in the high-pressure phase, resulting in a novel modification of the Ruddlesden-Popper structure. In contrast to the study by Zhao et al [19], no evidence for a second-order structural transition around 14 GPa was found either at room temperature or at 20 K.…”

“…The lower compressibility along the c axis in the tetragonal phase appears to be alleviated by the phase transition to monoclinic symmetry. A Vinet equation of state was fitted to the pressure-volume data of the tetragonal phase, yielding a bulk modulus of B 0 = 157(4) GPa [B 0 = 4.3(3)], in agreement with the literature [19].…”

“…We used helium as the pressure-transmitting medium (at room temperature and 20 K) and not neon as in Ref. [19] (at 25 K). The discrepancy between our studies may therefore arise from nonhydrostatic pressure conditions in the previous study.…”

“…In this context, application of pressure is an attractive control parameter, as it allows to continuously and isoelectronically tune the salient energy scales. Zhao et al reported a secondorder structural transition in Sr 3 Ir 2 O 7 at 14 GPa, accompanied by a reduction in resistivity [16,19]. However, high-pressure transport measurements by Zocco et al [20] have seen no evidence for this transition and instead report a gradual reduction of the electronic gap up to 104 GPa.…”

Pressure-Induced Confined Metal from the Mott InsulatorSr3Ir2O7Ding1, Yang2, Chen3 et al. 2016Phys. Rev. Lett.488820View full textAdd to dashboardCite

“…Its structure has been regarded to be tetragonal (I4/mmm, with a = 3.9026 Å and c = 20.9300 Å [16,17]), but other studies also reveal that the crystal symmetry could be orthorhombic (Bbcb, with a = 5.522 Å, b = 5.521 Å, and c = 20.917 Å [18]) or even monoclinic (C2/c, with a = 5.5185 Å, b = 5.5099 Å, and c = 20.935 Å [19] [12]. In addition, whereas Zhao et al reported a second-order structure transition at ~15 GPa, Donnere et al only discovered a first-order structure transition at ~54 GPa [17].…”