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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.83: Poster

Mittwoch, 24. März 2010, 14:00–18:00, Poster D1

Ground state phases of the spin-1/2 J₁–J₂–J₃ Heisenberg antiferromagnet on the square lattice — •Rachid Darradi¹, Johannes Reuther², Wolfram Brenig³, Johannes Richter⁴, and Peter Wölfle⁵ — ¹Institute for Theoretical Physics Technical University Braunschweig Mendelssohnstr. 3 38106 Braunschweig Germany — ²Institute for Condensed Matter Theory University Karlsruhe, Postfach 6980 76128 Karlsruhe Germany — ³Institute for Theoretical Physics Technical University Braunschweig Mendelssohnstr. 3 38106 Braunschweig Germany — ⁴Institute for Theoretical Physics, Otto-von-Guericke University Magdeburg, 39016 Magdeburg, Germany — ⁵Institute for Condensed Matter Theory University Karlsruhe, Postfach 6980 76128 Karlsruhe Germany

We investigate the zero-temperature phase diagram of the spin-1/2 frustrated J₁–J₂–J₃ Heisenberg Antiferromagnet on the square lattice. Using high orders coupled cluster method (CCM), Series expansion based on the flow equation method, and functional renormalization group (FRG), we have calculated the ground state energy, triplet excitations, the magnetic order parameter, and generalized susceptibilities. We determine the quantum critical lines for the semiclassical Néel, spiral and collinear phase, comparing our complementary approaches and contrasting our findings to other published results. Based on the susceptibilities which are related to valence-bond crystal order parameters we also discuss the nature of the quantum disordered phase separating the two semiclassical Néel and spiral phases.