5 years ago

4-spin plaquette singlet state in the Shastry–Sutherland compound SrCu2(BO3)2

4-spin plaquette singlet state in the Shastry–Sutherland compound SrCu2(BO3)2
K. Conder, R. A. Sadykov, Th. Strässle, C. Panagopoulos, Ch. Rüegg, M. Boehm, D. F. McMorrow, H. M. Rønnow, M. Ellerby, M. Jiménez–Ruiz, A. M. Läuchli, M. Stingaciu, E. Pomjakushina, G. Hamel, A. Schneidewind, S. Klotz, M. E. Zayed, S. S. Saxena, J. Larrea J., V. Pomjakushin
In the field of quantum magnetism, geometrically frustrated lattices generally imply major difficulties in analytical and numerical studies. For very few particular topologies, however, it has been shown that the ground state, at least, can be calculated exactly as for the Majumdar–Ghosh model15 that solves the J1J2 zigzag chain when J1 = 2J2. In two dimensions, the Shastry–Sutherland model2 consisting of an orthogonal dimer network of spin S = 1/2 was developed to be exactly solvable. For an inter-dimer J′ to intra-dimer J exchange ratio αJ/J ≤ 0.5 the ground state is a product of singlets on the strong bond J. Numerical calculations have further shown that this remains valid up to α ≤ ~0.7 and for small values of three-dimensional (3D) couplings J′′ between dimer layers. At the other end, for ~0.9 ≤ α the system approaches the well-known 2D square lattice, which is antiferromagnetically (AFM) ordered, albeit with significant quantum fluctuations that are believed to include resonating singlet correlations resulting in fractional excitations16. The phase diagram of the Shastry–Sutherland model, both with and without applied magnetic field, has been intensively studied by numerous theoretical and numerical approaches4. In the presence of magnetic field, magnetization plateaus at fractional values of the saturation magnetization corresponding to Mott insulator phases of dimer states, as well as possible superfluid and supersolid phases have been extensively studied7, 17, 18, 19. At zero field, the main unsolved issue is the existence and nature of an intermediate phase for ~0.7 ≤ α ≤ ~0.9. A variety of quantum phases and transitions between them have been predicted depending on the theoretical technique used: a direct transition from dimer singlet phase to AFM order2, 6, 7, or an intermediate phase with helical order5, columnar dimers11, valence bond crystal

Publisher URL: http://dx.doi.org/10.1038/nphys4190

DOI: 10.1038/nphys4190

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.