The J1-J2 Heisenberg model at and close to its z=4 quantum critical point

Authors :: Sirker, J.
Krivnov, V. Y.
Dmitriev, D. V.
Herzog, A.
Janson, O.
Nishimoto, S.
Drechsler, S. -L.
Richter, J.
Source :: Phys. Rev. B 84, 144403 (2011)
Publication Year :: 2011
Abstract: We study the frustrated J1-J2 Heisenberg model with ferromagnetic nearest neighbor coupling J1<0 and antiferromagnetic next-nearest neighbor coupling J2>0 at and close to the z=4 quantum critical point (QCP) at J1/J2=-4. The J1-J2 model plays an important role for recently synthesized chain cuprates as well as in supersymmetric Yang Mills theories. We study the thermodynamic properties using field theory, a modified spin-wave theory as well as numerical density-matrix renormalization group calculations. Furthermore, we compare with results for the classical model obtained by analytical methods and Monte-Carlo simulations. As one of our main results we present numerical evidence that the susceptibility at the QCP seems to diverge with temperature T as chi ~ T^{-1.2} in the quantum case in contrast to the classical model where chi ~ T^{-4/3}.<br />Comment: References added and other minor changes