Fractional Impurity Moments in Two-Dimensional Noncollinear Magnets

Alexander Wollny, Lars Fritz, and Matthias Vojta
Phys. Rev. Lett. 107, 137204 – Published 21 September 2011

Abstract

We study dilute magnetic impurities and vacancies in two-dimensional frustrated magnets with noncollinear order. Taking the triangular-lattice Heisenberg model as an example, we use quasiclassical methods to determine the impurity contributions to the magnetization and susceptibility. Most importantly, each impurity moment is not quantized but receives nonuniversal screening corrections due to local relief of frustration. At finite temperatures, where bulk long-range order is absent, this implies an impurity-induced magnetic response of Curie form, with a prefactor corresponding to a fractional moment per impurity. We also discuss the behavior in an applied magnetic field, where we find a singular linear-response limit for overcompensated impurities.

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  • Received 3 May 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.137204

© 2011 American Physical Society

Authors & Affiliations

Alexander Wollny1,2, Lars Fritz1, and Matthias Vojta2

  • 1Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
  • 2Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany

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Vol. 107, Iss. 13 — 23 September 2011

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