Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 52: Quantum Impurities and Kondo Physics
TT 52.10: Vortrag
Donnerstag, 4. April 2019, 12:00–12:15, H7
Possible topological effects seen by ESR in the Kondo insulator SmB6 doped by Gd. — Jean Carlo Souza1,2, P.F.S. Rosa3, •Jörg Sichelschmidt1, S. Wirth1, Z. Fisk4, and P.G. Pagliuso1 — 1MPI for Chemical Physics of Solids, Dresden — 2Instituto de Física Gleb Wataghin, UNICAMP, Campinas, SP, Brazil — 3Los Alamos National Laboratory, New Mexico 87545, USA — 4Department of Physics and Astronomy, University of California, Irvine, USA
We utilized Electron spin resonance (ESR) as a microscopic technique to explore the spin dynamics of Gd3+ substituted in the Kondo insulator SmB6. For Gd concentrations larger than 400 ppm the ESR spectra at T<30 K acquire a typical metallic line shape while the resistivity shows a Kondo-insulating bulk material. This demonstrates that the hybridization gap is closing locally around the Gd-site. For highly diluted Gd (200 ppm) the spectral shapes are affected by the diffusive transport of spins near the surface. The dependence on temperature, magnetic field, and microwave power provides a link between this diffusive ESR line shape to the presence of topological surface states. A similar result was reported for anomalous diffusive ESR effects for Nd3+ in the semimetal YBiPt [1]. Moreover, the temperature dependence of these diffusive ESR effects is similarly seen in the surface response of scanning tunneling spectroscopy [2].
[1] G. G. Lesseux et al., J. Phys. Condens. Matter 28, 125601 (2016) [2] L. Jiao et al., Nat. Commun. 7, 13762 (2016)