Standard model of the rare earths analyzed from the Hubbard I approximation

I. L. M. Locht, Y. O. Kvashnin, D. C. M. Rodrigues, M. Pereiro, A. Bergman, L. Bergqvist, A. I. Lichtenstein, M. I. Katsnelson, A. Delin, A. B. Klautau, B. Johansson, I. Di Marco, and O. Eriksson
Phys. Rev. B 94, 085137 – Published 22 August 2016

Abstract

In this work we examine critically the electronic structure of the rare-earth elements by use of the so-called Hubbard I approximation. From the theoretical side all measured features of both occupied and unoccupied states are reproduced, without significant deviations between observations and theory. We also examine cohesive properties like the equilibrium volume and bulk modulus, where we find, in general, a good agreement between theory and measurements. In addition, we have reproduced the spin and orbital moments of these elements as they are reflected from measurements of the saturation moment. We have also employed the Hubbard I approximation to extract the interatomic exchange parameters of an effective spin Hamiltonian for the heavy rare earths. We show that the Hubbard I approximation gives results which are consistent with calculations where 4f electrons are treated as core states for Gd. The latter approach was also used to address the series of the heavy/late rare earths. Via Monte Carlo simulations we obtained ordering temperatures which reproduce measurements within about 20%. We have further illustrated the accuracy of these exchange parameters by comparing measured and calculated magnetic configurations for the heavy rare earths and the magnon dispersion for Gd. The Hubbard I approximation is compared to other theories of the electronic structure, and we argue that it is superior. We discuss the relevance of our results in general and how this makes it possible to treat the electronic structure of materials containing rare-earth elements, such as permanent magnets, magnetostrictive compounds, photovoltaics, optical fibers, topological insulators, and molecular magnets.

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  • Received 10 December 2015
  • Revised 14 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.085137

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

I. L. M. Locht1,2, Y. O. Kvashnin1, D. C. M. Rodrigues1,3, M. Pereiro1, A. Bergman1, L. Bergqvist4,5, A. I. Lichtenstein6, M. I. Katsnelson2, A. Delin1,4,5, A. B. Klautau3, B. Johansson1,7, I. Di Marco1, and O. Eriksson1

  • 1Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
  • 2Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
  • 3Faculdade de Física, Universidade Federal do Pará, Belém, Pará, Brazil
  • 4Department of Materials and Nanophysics, School of Information and Communication Technology, Electrum 229, Royal Institute of Technology (KTH), SE-164 40 Kista, Sweden
  • 5Swedish e-Science Research Centre (SeRC), KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
  • 6Hamburg University, Institute for Theoretical Physics, D-20355 Hamburg, Germany
  • 7Department of Material Science and Engineering, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden

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Issue

Vol. 94, Iss. 8 — 15 August 2016

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