Competing orders at higher-order Van Hove points

Physical review. B./Physical review. B, vol. 102

Abstract

Van Hove points are special points in the energy dispersion, where the density of states exhibits analytic singularities. When a Van Hove point is close to the Fermi level, tendencies towards density wave orders, Pomeranchuk orders, and superconductivity can all be enhanced, often in more than one channel, leading to a competition between different orders and unconventional ground states. Here we consider the effects from higher-order Van Hove points, around which the dispersion is flatter than near a conventional Van Hove point, and the density of states has a power-law divergence. We argue that such points are present in intercalated graphene and other materials. We use an effective low-energy model for electrons near higher-order Van Hove points and analyze the competition between different ordering tendencies using an unbiased renormalization-group approach. For purely repulsive interactions, we find that two key competitors are ferromagnetism and chiral superconductivity. For a small attractive interaction, we find an unconventional spin Pomeranchuk order, in wich the spin oder parameter winds around the Fermi surface. The supermetal state, predicted for a single higher-order Van Hove point, is an unstable fixed point in our case.

Authors 4

1. Laura Classen

   University of Minnesota · Brookhaven National Laboratory

   Affiliation as printed

   Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

   School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA

2. Andrey V. Chubukov

   University of Minnesota

   Affiliation as printed

   School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA

3. Carsten Honerkamp Aachen Institute for Theoretical Solid State Physics

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Solid State Physics, RWTH Aachen University, 52074 Aachen, Germany

   JARA-FIT, Jülich Aachen Research Alliance and Fundamentals of Future Information Technology, 52056 Aachen, Germany

4. Michael M. Scherer

   University of Cologne

   Affiliation as printed

   Institut für Theoretische Physik, Universität zu Köln, 50937 Cologne, Germany