1/T1 nuclear relaxation time of k-(BEDT-TTF)2Cu[N(CN)2]Cl: a frustrated spin model

HAMAD, I. J.; ADOLFO EMILIO TRUMPER; WZIETEK, P.; LEFEBVRE, S.; MANUEL, LO

Trinidad y Tobago

Workshop; Workshop "Mottness and Quantum Criticality"; 2005

Pan American advanced Studies Institutes (PASI)

We analyze the validity of the spatially anisotropic triangular Heisenberg model to describe the antiferromagnetic phase of the organic salt $\kappa-(BEDT-TTF)_ 2 Cu [N(CN)_2] Cl$. We compare the model predictions with previous and new performed NMR experiments. We compute the $1/T_1$ relaxation time by means of the modified spin wave theory. The strong suppression of the nuclear relaxation time observed experimentally under varying pressure and magnetic field is qualitatively well reproduced by the model. Particularly, we could identify the magnetic frustration as the microscopic counterpart of pressure. We conclude that this simple model turns out appropriate to describe qualitatively well the antiferromagnetic phase of the $\kappa$ compounds.