Starts 27 Feb 2013 16:30
Ends 27 Feb 2013 20:00
Central European Time
Leonardo da Vinci Building Luigi Stasi Seminar Room
Strada Costiera, 11 I - 34151 Trieste (Italy)
For the past 25 years, the Heisenberg S = 1/2 ladder remains the most important model in quantum magnetism. It combines the essence of quantum spin fluctuations with topological peculiarities of one dimension. The vast amount of theoretical work performed over the years yielded a comprehensive picture of spin correlations in this model, and their evolution in applied magnetic fields. Unfortunately, good experimental realizations and sufficiently accurate numerical results remained elusive. The situation changed drastically in the past couple of years, due to progress in material synthesis, neutron scattering instrumentation and algorithm development. We are now close to claiming that the spectral and thermodynamic properties of the quintessential J_rung-J_leg Heisenberg ladder model are completely understood at the quantitative level. Particularly striking are recent results on spin excitations in the strong-leg ladder material DIMPY, obtained in the gapped spin liquid [1-3] and gapless Tomonaga-Luttinger spin liquid phases [3]. At the same time, just slightly more complex ladder systems, those showing disorder [4], geometric frustration [5,6] or a coupling to the crystal lattice [7], present new challenges that we are beginning to tackle. References 1. T. Hong et al., Phys. Rev. Lett. 105, 137207 (2010). 2. D. Schmidiger et al., Phys. Rev. B 84,144421 (2011) 3. D. Schmidiger et al., Phys. Rev. Lett. 108, 167201 (2012). 4. T. Hong et al., Phys. Rev. B 81, [Rapid] 060410 (2010). 5. V. O. Garlea, et al., Phys. Rev. Lett. 100, 037206 (2008). 6. V. O. Garlea, et al., Phys. Rev. B 79, [Rapid] 060404 (2009). 7. F. Schrettle, et al., Phys. Rev. B [Rapid]-in press, arXiv:1203.3127v1.
  • M. Poropat