Phonon softening and anomalous mode near the xc = 0.5 quantum critical point inCa2-xSrxRuO4

Published

May 4, 2009

Author(s)

R. G. Moore, M. D. Lumsden, M. B. Stone, Jiandi Zhang, Ying Chen, Jeffrey Lynn, R. Jin, D Mandrus, E. W. Plummer

Abstract

Inelastic neutron scattering is used to measure the temperature-dependent phonon dispersion in Ca2−xSrxRuO4(x=0.4,0.6). The in-plane Σ4 octahedral tilt mode softens significantly at the zone boundary of the high-temperature tetragonal (HTT) I41/acd structure as the temperature approaches the transition to a low-temperature orthorhombic (LTO) Pbca phase. This behavior is similar to that in La2CuO4, but an inelastic feature that is not found in the cuprate is present. An anomalous phonon mode is observed at energy transfers greater than the Σ4, albeit with similar dispersion. This anomalous phonon mode never softens below ∼5 meV, even for temperatures below the HTT-LTO transition. This mode is attributed to the presence of intrinsic structural disorder within the I41/acd tetragonal structure of the doped ruthenate.

Citation

Physical Review B

Volume

79

Issue

17

Pub Type

Journals

Download Paper

https://doi.org/10.1103/PhysRevB.79.172301

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Keywords

inelastic neutron scattering, soft phonons, structural phase transition, quantum critical point, anomalous phonon mode

Citation

Moore, R. , Lumsden, M. , Stone, M. , Zhang, J. , Chen, Y. , Lynn, J. , Jin, R. , Mandrus, D. and Plummer, E. (2009), Phonon softening and anomalous mode near the x_c = 0.5 quantum critical point inCa_2-xSr_xRuO₄, Physical Review B, [online], https://doi.org/10.1103/PhysRevB.79.172301, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=610023 (Accessed December 10, 2024)