title: Quantum Stoner-Wohlfarth Model.
abstract: The quantum mechanical counterpart of the famous Stoner-Wohlfarth model-an easy-axis magnet in a tilted magnetic field-is studied theoretically and through simulations as a function of the spin size S in a sweeping longitudinal field. Beyond the classical Stoner-Wohlfarth transition, the sweeping field-induced adiabatic change of states slows down as S increases, leading to a dynamical quantum phase transition. This result gives us new insights to describe the collapse of the metastability from the viewpoint of a critical phenomenon associated with the Landau-Zener tunneling gaps. Furthermore, a beating of the amplitude of the magnetization (the spin-length fidelity) is discovered after the Stoner-Wohlfarth transition. The period of the beating, confirmed analytically, arises from a new type of quantum phase factor.
authors: Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan.
authors: Takuya
authors: T
authors: Hatomura
authors: Institut Néel, CNRS, F-38042 Grenoble, France.|Université Grenoble-Alpes/Institut Néel, F-38042 Grenoble, France.
authors: Bernard
authors: B
authors: Barbara
authors: Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan.|CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors: Seiji
authors: S
authors: Miyashita