Anomalous spin correlations and excitonic instability of interacting 2D Weyl fermions

Abstract

Finding correlations in a Dirac-cone material Researchers have long been on the lookout for signatures of electron-electron interactions in materials whose electrons have linear energy dispersions represented by Dirac cones, such as graphene. However, these effects have remained frustratingly small. Hirata et al. used nuclear magnetic resonance to study the layered organic material α-(BEDT-TTF) 2 I 3 , in which a phase featuring Dirac cones is known to be adjacent to one with enhanced electronic correlations. The unusual temperature dependence of spin-related properties in this material indicated strong correlations among the linearly dispersing electrons. Science , this issue p. 1403