Publications associated with Quantum Matter in High Magnetic Fields

La2SrCr2O7: Controlling the Tilting Distortions of n = 2 Ruddlesden-Popper Phases through A-Site Cation Order.

Inorganic chemistry 55 (2016) 8951-8960

R Zhang, BM Abbett, G Read, F Lang, T Lancaster, TT Tran, PS Halasyamani, SJ Blundell, NA Benedek, MA Hayward

Structural characterization by neutron diffraction, supported by magnetic, SHG, and μ(+)SR data, reveals that the n = 2 Ruddlesden-Popper phase La2SrCr2O7 adopts a highly unusual structural configuration in which the cooperative rotations of the CrO6 octahedra are out of phase in all three Cartesian directions (ΦΦΦz/ΦΦΦz; a(-)a(-)c(-)/a(-)a(-)c(-)) as described in space group A2/a. First-principles DFT calculations indicate that this unusual structural arrangement can be attributed to coupling between the La/Sr A-site distribution and the rotations of the CrO6 units, which combine to relieve the local deformations of the chromium-oxygen octahedra. This coupling suggests new chemical "handles" by which the rotational distortions or A-site cation order of Ruddlesden-Popper phases can be directed to optimize physical behavior. Low-temperature neutron diffraction data and μ(+)SR data indicate La2SrCr2O7 adopts a G-type antiferromagnetically ordered state below TN ∼ 260 K.

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