Spin excitations in a single La2CuO4 layer

M. P. M. Dean*, R. S. Springell, C. Monney, K. J. Zhou, J. Pereiro, I. Bozovic, B. Dalla Piazza, H. M. Ronnow, E. Morenzoni, J. van den Brink, T. Schmitt, J. P. Hill

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

92 Citations (Scopus)

Abstract

Cuprates and other high-temperature superconductors consist of two-dimensional layers that are crucial to their properties. The dynamics of the quantum spins in these layers lie at the heart of the mystery of the cuprates(1-7). In bulk cuprates such as La2CuO4, the presence of a weak coupling between the two-dimensional layers stabilizes a three-dimensional magnetic order up to high temperatures. In a truly two-dimensional system however, thermal spin fluctuations melt long-range order at any finite temperature(8). Here, we measure the spin response of isolated layers of La2CuO4 that are only one-unit-cell-thick. We show that coherent magnetic excitations, magnons, known from the bulk order, persist even in a single layer of La2CuO4, with no evidence for more complex correlations such as resonating valence bond correlations(9-11). These magnons are, therefore, well described by spin-wave theory (SWT). On the other hand, we also observe a high-energy magnetic continuum in the isotropic magnetic response that is not well described by two-magnon SWT, or indeed any existing theories.

Original languageEnglish
Pages (from-to)850-854
Number of pages5
JournalNature Materials
Volume11
Issue number10
DOIs
Publication statusPublished - Oct 2012

Keywords

  • HEISENBERG-ANTIFERROMAGNET
  • SQUARE LATTICE
  • TEMPERATURE SUPERCONDUCTOR
  • OXIDES
  • WAVES
  • PHASE

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