Interplay of Electronic and Spin Degrees in Ferromagnetic SrRuO_{3}: Anomalous Softening of the Magnon Gap and Stiffness

K Jenni; S Kunkemöller; D Brüning; T Lorenz; Y Sidis; A Schneidewind; A A Nugroho; A Rosch; D I Khomskii; M Braden

doi:10.1103/PhysRevLett.123.017202

Interplay of Electronic and Spin Degrees in Ferromagnetic SrRuO_{3}: Anomalous Softening of the Magnon Gap and Stiffness

Phys Rev Lett. 2019 Jul 3;123(1):017202. doi: 10.1103/PhysRevLett.123.017202.

Authors

K Jenni¹, S Kunkemöller¹, D Brüning¹, T Lorenz¹, Y Sidis², A Schneidewind³, A A Nugroho⁴, A Rosch⁵, D I Khomskii¹, M Braden¹

Affiliations

¹ II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany.
² Laboratoire Léon Brillouin, C.E.A./C.N.R.S., F-91191 Gif-sur-Yvette CEDEX, France.
³ Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstraße 1, 85748 Garching, Germany.
⁴ Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jalan Ganesha 10, 40132 Bandung, Indonesia.
⁵ Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77a, D-50937 Köln, Germany.

PMID: 31386396
DOI: 10.1103/PhysRevLett.123.017202

Abstract

The magnon dispersion of ferromagnetic SrRuO_{3} was studied by inelastic neutron scattering experiments on single crystals as a function of temperature. Even at low temperature the magnon modes exhibit substantial broadening pointing to strong interaction with charge carriers. We find an anomalous temperature dependence of both the magnon gap and the magnon stiffness, which soften upon cooling in the ferromagnetic phase. Both effects trace the temperature dependence of the anomalous Hall effect and can be attributed to the impact of Weyl points, which results in the same relative renormalization in the spin stiffness and magnon gap.