title: Pressure effect on the structural transition and suppression of the high-spin state in the triple-layer T'-La4Ni3O8.
abstract: We report a comprehensive high-pressure study on the triple-layer T'-La4Ni3O8 with a suite of experimental probes, including structure determination, magnetic, and transport properties up to 50 GPa. Consistent with a recent ab inito calculation, application of hydrostatic pressure suppresses an insulator-metal spin-state transition at P(c)≈6  GPa. However, a low-spin metallic phase does not emerge after the high-spin state is suppressed to the lowest temperature. For P>20  GPa, the ambient T' structure transforms gradually to a T(†)-type structure, which involves a structural reconstruction from fluorite La-O2-La blocks under low pressures to rock-salt LaO-LaO blocks under high pressures. Absence of the metallic phase under pressure has been discussed in terms of local displacements of O2- ions in the fluorite block under pressure before a global T(†) phase is established.
authors.affiliation: Materials Science and Engineering Program/Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: J-G
authors.initials: JG
authors.lastname: Cheng
authors.forename: J-S
authors.initials: JS
authors.lastname: Zhou
authors.forename: J B
authors.initials: JB
authors.lastname: Goodenough
authors.forename: H D
authors.initials: HD
authors.lastname: Zhou
authors.forename: K
authors.initials: K
authors.lastname: Matsubayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Uwatoko
authors.forename: P P
authors.initials: PP
authors.lastname: Kong
authors.forename: C Q
authors.initials: CQ
authors.lastname: Jin
authors.forename: W G
authors.initials: WG
authors.lastname: Yang
authors.forename: G Y
authors.initials: GY
authors.lastname: Shen