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arXiv · 1411.4055

Pairing gaps near ferromagnetic quantum critical points

Matthias Einenkel·Hendrik Meier·Catherine Pépin·Konstantin B. Efetov
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Abstract

We address the quantum-critical behavior of a two-dimensional itinerant ferromagnetic systems described by a spin-fermion model in which fermions interact with close to critical bosonic modes. We consider Heisenberg ferromagnets, Ising ferromagnets, and the Ising nematic transition. Mean-field theory close to the quantum critical point predicts a superconducting gap with spin-triplet symmetry for the ferromagnetic systems and a singlet gap for the nematic scenario. Studying fluctuations in this ordered phase using a nonlinear sigma model, we find that these fluctuations are not suppressed by any small parameter. As a result, we find that a superconducting quasi-long-range order is still possible in the Ising-like models but long-range order is destroyed in Heisenberg ferromagnets.

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Matthias Einenkel, Hendrik Meier, Catherine Pépin, Konstantin B. Efetov. 2014-11-14. Pairing gaps near ferromagnetic quantum critical points. https://doi.org/10.1103/physrevb.91.064507

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