QUANTUM SPIN SYSTEMS

    Current work in quantum computing and spintronics is boosting renewed interest in basic models of disordered quantum magnets. Two main ingredients are singled out as crucial to set the physical behavior of these systems: strong interaction and frustration. It is well known that the interplay between them leads to a rich variety of magnetically ordered phases, including conventional commensurate or incommensurate spin-density waves as well as the more exotic spin-glass state.
    One example of real systems with a spin-glass phase at low temperature is the compound Li(1-x)Ho(x)YF(4) which is a dipolar coupled random magnet. Another notable example is the LiV(2)O(4) compound in which the magnetic V atoms are placed at the vertices of a phyrochlore-like structure which produces strong frustration and a spin-glass state. Finally, we have the cuprate superconductors, with vast experimental evidence that a glassy phase exists at low temperatures within a narrow range of doping concentrations between the antiferromagnetic and superconducting phases.
    Other fascinating spin systems are the Heisenberg magnets in two-dimensional triangular and Kagome lattices. Numerical studies have been of great help to show that the triangular lattice has planar antiferromagnetic order while the nature of the ground state of the Kagome lattice still remains a controversial issue.
    I am interested in:

  • Disordered quantum magnets.

  • S=1/2 Heisenberg model in triangular and Kagome lattices.

      Recent publications:
    • Quantum Magnets with Anisotropic Infinite Range Random Interactions.
      Liliana Arrachea and Marcelo J. Rozenberg.
      Special issue of Biophysical Chemistry 115, 135 (2005).
    • From the triangular to the kagome lattice: Following the footprints of the ordered state.
      Liliana Arrachea, Luca Capriotti, Sandro Sorella.
      Physical Review B 69, 224414 (2004).
    • Melting transition of an Ising glass driven by a magnetic field.
      Liliana Arrachea, Denis Dalidovich and Vladimir Dobrosavljevic and M. Rozenberg.
      Physical Review B 69, 064419 (2004).
    • The infinite-range quantum random Heisenberg magnet.
      Liliana Arrachea and Marcelo Rozenberg.
      Physical Review B 66, 224430 (2002).
    • Infinite-range quantum random magnets.
      Marcelo Rozenberg and Liliana Arrachea.
      Physica B 312, 416 (2002).
    • Dynamical response of quantum spin-glass models at T=0.
      Liliana Arrachea and M. J. Rozenberg.
      Physical Review Letters 86, 5172 (2001)