Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Correlated Electrons: Quantum-Critical Phenomena - Theory

TT 50.1: Vortrag

Dienstag, 1. April 2014, 14:00–14:15, BEY 81

Detailed analysis of critical points in coupled spin dimer systems — •Sebastian Eggert¹, Dominik Straßel¹, and Peter Kopietz² — ¹Fachbereich Physik, Technische Universität Kaiserslautern — ²Fachbereich Physik, Goethe Universität Frankfurt

Spin dimer systems are a promising playground for the detailed study of quantum phase transitions. In many cases it is sufficient to use the magnetic field as the tuning parameter in order to reach interesting non-trivial critical points. Depending on the temperature it is in principle possible to observe a crossover from the characteristic scaling near the critical point to the behavior of a finite temperature phase transition. In order to quantitatively demonstrate those effects and inspired by recent experiments we have started large scale quantum Monte Carlo simulations in order to analyze several different physical quantities in spin dimer systems, namely the susceptibility, the magneto-caloric effect, the structure factor and the spin stiffness. We discuss in detail how the phase transitions (quantum and finite temperature) are manifest in the characteristic scaling behavior near critical points by comparing them with interacting boson theories. The results give a unified picture of the full quantum and finite temperature phase diagram.