Dimensional Reduction in BaCuSi<sub>2</sub>O<sub>6</sub> Investigated by Neutron Scattering

ORAL

Abstract

Quasi low-dimensional systems tipically display a dimensional crossover into 3D behavior either because of a diverging correlation length close to a critical point or due to vanishing thermal fluctuations when approaching zero temperature. Contrary to this, the quantum magnet BaCuSi2O6, which consists of stacked 2D layers hosting spin dimers, undergoes a dimensional reduction from 3D to 2D in close vicinity to the quantum critical point to its Bose Einstein Condensate phase [1]. Mechanisms for this dimensional reduction were proposed based on frustration of the interlayer exchange resulting from an assumed antiferromagnetic intralayer exchange. However, density-functional theory calculations suggest a ferromagnetic intralayer exchange which would render such a frustration impossible [2]. We have performed high-resolution neutron spectroscopy experiments and calculated the excitation spectrum for various dimer models. Our results suggest that the intralayer exchange is ferromagnetic, while there exist at least three different dimer types in BaCuSi2O6. We conclude that the existence of different dimer types might lead to 2D behavior in close vicinity to the quantum critical point.

[1] C. E. Sebastian et al., Nature 441, 617 (2006).
[2] V. V. Mazurenko et al., PRL 112, 107202 (2014).

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Presenters

  • Stephan Allenspach

    • Research with Neutrons and Muons, Paul Scherrer Institute

Authors

  • Stephan Allenspach

    • Research with Neutrons and Muons, Paul Scherrer Institute

  • Alun M Biffin

    • Research with Neutrons and Muons, Paul Scherrer Institute

  • Uwe Stuhr

    • Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute

  • Gregory Tucker

    • Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute

  • Seiko Ohira-Kawamura

    • Japan Atomic Energy Agency
    • J-PARC Center

  • Maiko Kofu

    • Material and Life Science Experimental Facility, Japan Proton Accelerator Research Complex
    • J-PARC Center

  • David J. Voneshen

    • ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council
    • ISIS Facility, Rutherford Appleton Laboratory
    • ISIS Facility, RAL

  • Nicolas Laflorencie

    • Laboratoire de Physique Théorique, Université de Toulouse
    • CNRS and University of Toulouse
    • CNRS & Toulouse university

  • Frederic Mila

    • EPFL Lausanne
    • Institute of Theoretical Physics, Ecole Polytechnique Fédérale Lausanne (EPFL)
    • Institute of Physics, École Polytechnique Fédérale de Lausanne
    • Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL)

  • Christian Ruegg

    • Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen
    • Research with Neutrons and Muons, Paul Scherrer Institute
    • Neutrons and Muons Research Division, Paul Scherrer Institute