title: Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor.
abstract: The Coulomb interaction among massless Dirac fermions in graphene is unscreened around the isotropic Dirac points, causing a logarithmic velocity renormalization and a cone reshaping. In less symmetric Dirac materials possessing anisotropic cones with tilted axes, the Coulomb interaction can provide still more exotic phenomena, which have not been experimentally unveiled yet. Here, using site-selective nuclear magnetic resonance, we find a non-uniform cone reshaping accompanied by a bandwidth reduction and an emergent ferrimagnetism in tilted Dirac cones that appear on the verge of charge ordering in an organic compound. Our theoretical analyses based on the renormalization-group approach and the Hubbard model show that these observations are the direct consequences of the long-range and short-range parts of the Coulomb interaction, respectively. The cone reshaping and the bandwidth renormalization, as well as the magnetic behaviour revealed here, can be ubiquitous and vital for many Dirac materials.
authors: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.|Laboratoire National des Champs Magnétiques Intenses, UPR 3228 CNRS, EMFL, UGA, UPS and INSA, Boite Postale 166, Grenoble, Cedex 9 38042, France.
authors: Michihiro
authors: M
authors: Hirata
authors: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors: Kyohei
authors: K
authors: Ishikawa
authors: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors: Kazuya
authors: K
authors: Miyagawa
authors: Department of Physics, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors: Masafumi
authors: M
authors: Tamura
authors: Laboratoire National des Champs Magnétiques Intenses, UPR 3228 CNRS, EMFL, UGA, UPS and INSA, Boite Postale 166, Grenoble, Cedex 9 38042, France.
authors: Claude
authors: C
authors: Berthier
authors: Université Grenoble Alpes and CNRS, Laboratoire de Physique et Modélisation des Milieux Condensés UMR 5493, 25 rue des Martyrs, Grenoble 38042, France.
authors: Denis
authors: D
authors: Basko
authors: Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Akito
authors: A
authors: Kobayashi
authors: Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Genki
authors: G
authors: Matsuno
authors: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors: Kazushi
authors: K
authors: Kanoda