DPG Phi
Verhandlungen
Verhandlungen
DPG

Dresden 2011 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

TT: Fachverband Tiefe Temperaturen

TT 23: CE: Quantum-Critical Phenomena 2

TT 23.4: Talk

Tuesday, March 15, 2011, 11:15–11:30, HSZ 105

Thermodynamics of the spin-dimer NiCl2-4SC(NH2)2 system at the magnetic-field-induced quantum phase transition — •Alexander Steppke1, Robert Kuechler1, Luis Pedrero1, Manuel Brando1, Armando Paduan-Filho2, Christian Batista3, Franziska Weickert3, Vivien Zapf3, Marcelo Jaime3, and Frank Steglich11Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany — 2Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil — 3Los Alamos National Laboratory, Los Alamos, USA

The concept of universality class in magnetic systems undergoing a quantum phase transition (QPT) can be tested in so-called quantum magnets, where the local spins are coupled forming ladders (TlCuCl3), planes of dimers (BaCuSi2O6) or weakly coupled chains of S=1 Ni atoms, as in the organic system NiCl2-4SC(NH2)2 (DTN). In DTN the Ni2+ single ion anisotropy D = 8.9 K opens an energy gap between the Sz = 0 ground state and the Sz = ± 1 first excited state. At a magnetic field Hc1 ≈ 2 T the gap closes and a transition into an XY-antiferromagnetic ordered state is induced at low temperatures. Such a QPT belongs to the d=3 and z=2 universality class and the following theoretical laws are predicted: The magnetization MTd/z, the phase boundary line (HHc1)∝ Tcd/z, the thermal and magnetic Grüneisen ratios are expected to follow T−1. We have investigated the temperature and field dependences of all these thermodynamic quantities in the temperature range 0.05 ≤ T ≤ 5 K.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2011 > Dresden