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arXiv · 1108.6064

Quantum criticality of dipolar spin chains

Aldo Isidori·Annika Ruppel·Andreas Kreisel·Peter Kopietz·Alexander Mai·Reinhard M. Noack
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Abstract

We show that a chain of Heisenberg spins interacting with long-range dipolar forces in a magnetic field h perpendicular to the chain exhibits a quantum critical point belonging to the two-dimensional Ising universality class. Within linear spin-wave theory the magnon dispersion for small momenta k is [Delta^2 + v_k^2 k^2]^{1/2}, where Delta^2 \propto |h - h_c| and v_k^2 \propto |ln k|. For fields close to h_c linear spin-wave theory breaks down and we investigate the system using density-matrix and functional renormalization group methods. The Ginzburg regime where non-Gaussian fluctuations are important is found to be rather narrow on the ordered side of the transition, and very broad on the disordered side.

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Aldo Isidori, Annika Ruppel, Andreas Kreisel, Peter Kopietz, Alexander Mai, Reinhard M. Noack. 2011-08-30. Quantum criticality of dipolar spin chains. https://doi.org/10.1103/physrevb.84.184417

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