Quantum Antiferromagnetism: from Numerical Simulations to Systematic Effective Field Theories

by Uwe-Jens Wiese (Universitat Bern)

Friday 28 Nov 2008, 14:15 → 15:15 Europe/Zurich

Universite de Geneve, Auditoire Stueckelberg

Lightly doped quantum antiferromagnets are the precursors of high-temperature superconductors. The Goldstone bosons of antiferromagnetism are spin waves or magnons. In analogy to baryon chiral perturbation theory for the pseudo-Goldstone pions and nucleons in QCD, systematic low-energy effective field theories are developed for magnons and holes in lightly doped antiferromagnets, both on the square and on the honeycomb lattice. Two-hole states bound by magnon exchange are a condensed matter analog of the deuteron, while spiral phases of the staggered magnetization are analogous to pion condensation in dense nuclear matter. The determination of the low-energy parameters of the effective theory by high-precision numerical simulations of the t-J model is also discussed.