Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: CE: Spin Systems and Itinerant Magnets

TT 22.4: Talk

Wednesday, March 24, 2010, 10:15–10:30, H21

Spin dynamics in nearly critical magnets with quenched disorder — •Matthias Vojta — Institut für Theoretische Physik, Universität zu Köln, Germany

Quanten phase transitions in quantum magnets, with coupled-dimer systems being prominent examples, have been extensively studied both experimentally and theoretically. In the absence of quenched disorder, the excitation spectrum near criticality is essentially understood. In contrast, relatively little is known about dynamical properties in the disordered case. Here we present numerical results for the fluctuation spectrum of coupled-dimer magnets with quenched disorder of random-mass type, obtained by a generalization of the bond-operator method. The results are directly applicable to doped dimer materials like (K,Tl)CuCl₃ and will also be discussed with an eye towards disordered stripe phases in cuprate superconductors.