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Title: Anharmonic rattling vibrations effects in the ESR of Er 3+ doped SmB 6 Kondo insulator

Abstract

We report X-band Electron Spin Resonance (ESR) experiments on ≈ 0.2% and ≈ 0.7 % Er 3+ doped SmB 6 at low temperature (4 K - 40 K). The crystal field ground state of Er 3+ in SmB 6 is a Γ 8 quartet with a nearby Γ 6 excited doublet. The angular dependence of the resonances is not consistent with transitions between pure cubic crystal field states. The data were interpreted in terms of a dynamic Jahn-Teller (JT) effect by a coupling to Γ 3 vibrational modes, which we propose to originate from the rattling of the small Er 3+ ions in the large SmB6 cage. Our data show an anisotropic pair of E and E’ resonances at g ≈ 4.4 and two nearly isotropic signals at g ≈ 5.8, one intense and narrow (A vibrational mode) and the other broad and faint, which we attribute to Er 3+ ions at lattice sites which are strongly affected by strain, defects and/or extrinsic Al impurities that inhibits the JT effects. Our results are in general consistent with those previously reported by Sturm et al. In addition to the angular dependence of the lines, we discuss the intensities, g-values and themore » linewidths of the Er 3+ transitions as a function of temperature.« less

Authors:
 [1];  [2];  [3];  [4];  [1];  [1];  [5]
  1. Univ. Estadual de Campinas, Campinas (Brazil)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of California, Irvine, CA (United States)
  4. Florida State Univ., Tallahassee, FL (United States)
  5. Univ. Estadual de Campinas, Campinas (Brazil); Univ. Federal do ABC, Santo André (Brazil)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1349331
Alternate Identifier(s):
OSTI ID: 1375881; OSTI ID: 1421272
Report Number(s):
LA-UR-17-23578
Journal ID: ISSN 2158-3226; AAIDBI
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Published Article
Journal Name:
AIP Advances
Additional Journal Information:
Journal Volume: 7; Journal Issue: 5; Journal ID: ISSN 2158-3226
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Material Science

Citation Formats

Lesseux, G. G., Rosa, P. F. S., Fisk, Z., Schlottmann, P., Pagliuso, P. G., Urbano, R. R., and Rettori, C. Anharmonic rattling vibrations effects in the ESR of Er3+ doped SmB6 Kondo insulator. United States: N. p., 2017. Web. doi:10.1063/1.4974914.
Lesseux, G. G., Rosa, P. F. S., Fisk, Z., Schlottmann, P., Pagliuso, P. G., Urbano, R. R., & Rettori, C. Anharmonic rattling vibrations effects in the ESR of Er3+ doped SmB6 Kondo insulator. United States. doi:10.1063/1.4974914.
Lesseux, G. G., Rosa, P. F. S., Fisk, Z., Schlottmann, P., Pagliuso, P. G., Urbano, R. R., and Rettori, C. Mon . "Anharmonic rattling vibrations effects in the ESR of Er3+ doped SmB6 Kondo insulator". United States. doi:10.1063/1.4974914.
@article{osti_1349331,
title = {Anharmonic rattling vibrations effects in the ESR of Er3+ doped SmB6 Kondo insulator},
author = {Lesseux, G. G. and Rosa, P. F. S. and Fisk, Z. and Schlottmann, P. and Pagliuso, P. G. and Urbano, R. R. and Rettori, C.},
abstractNote = {We report X-band Electron Spin Resonance (ESR) experiments on ≈ 0.2% and ≈ 0.7 % Er3+ doped SmB6 at low temperature (4 K - 40 K). The crystal field ground state of Er3+ in SmB6 is a Γ8 quartet with a nearby Γ6 excited doublet. The angular dependence of the resonances is not consistent with transitions between pure cubic crystal field states. The data were interpreted in terms of a dynamic Jahn-Teller (JT) effect by a coupling to Γ3 vibrational modes, which we propose to originate from the rattling of the small Er3+ ions in the large SmB6 cage. Our data show an anisotropic pair of E and E’ resonances at g ≈ 4.4 and two nearly isotropic signals at g ≈ 5.8, one intense and narrow (A vibrational mode) and the other broad and faint, which we attribute to Er3+ ions at lattice sites which are strongly affected by strain, defects and/or extrinsic Al impurities that inhibits the JT effects. Our results are in general consistent with those previously reported by Sturm et al. In addition to the angular dependence of the lines, we discuss the intensities, g-values and the linewidths of the Er3+ transitions as a function of temperature.},
doi = {10.1063/1.4974914},
journal = {AIP Advances},
number = 5,
volume = 7,
place = {United States},
year = {Mon Jan 23 00:00:00 EST 2017},
month = {Mon Jan 23 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4974914

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  • We report X-band Electron Spin Resonance (ESR) experiments on ≈ 0.2% and ≈ 0.7 % Er 3+ doped SmB 6 at low temperature (4 K - 40 K). The crystal field ground state of Er 3+ in SmB 6 is a Γ 8 quartet with a nearby Γ 6 excited doublet. The angular dependence of the resonances is not consistent with transitions between pure cubic crystal field states. The data were interpreted in terms of a dynamic Jahn-Teller (JT) effect by a coupling to Γ 3 vibrational modes, which we propose to originate from the rattling of the small Ermore » 3+ ions in the large SmB6 cage. Our data show an anisotropic pair of E and E’ resonances at g ≈ 4.4 and two nearly isotropic signals at g ≈ 5.8, one intense and narrow (A vibrational mode) and the other broad and faint, which we attribute to Er 3+ ions at lattice sites which are strongly affected by strain, defects and/or extrinsic Al impurities that inhibits the JT effects. Our results are in general consistent with those previously reported by Sturm et al. In addition to the angular dependence of the lines, we discuss the intensities, g-values and the linewidths of the Er 3+ transitions as a function of temperature.« less
  • In this paper, using inelastic neutron scattering, we map a 14 meV coherent resonant mode in the topological Kondo insulator SmB 6 and describe its relation to the low energy insulating band structure. The resonant intensity is confined to the X and R high symmetry points, repeating outside the first Brillouin zone and dispersing less than 2 meV, with a 5d-like magnetic form factor. We present a slave-boson treatment of the Anderson Hamiltonian with a third neighbor dominated hybridized band structure. This approach produces a spin exciton below the charge gap with features that are consistent with the observed neutronmore » scattering. Finally, we find that maxima in the wave vector dependence of the inelastic neutron scattering indicate band inversion.« less
  • There has been considerable interest in exploiting the spin degrees of freedom of electrons for potential information storage and computing technologies. Topological insulators (TIs), a class of quantum materials, have special gapless edge/surface states, where the spin polarization of the Dirac fermions is locked to the momentum direction. This spin–momentum locking property gives rise to very interesting spin-dependent physical phenomena such as the Edelstein and inverse Edelstein effects. However, the spin injection in pure surface states of TI is very challenging because of the coexistence of the highly conducting bulk states. Here, we experimentally demonstrate the spin injection and observemore » the inverse Edelstein effect in the surface states of a topological Kondo insulator, SmB 6. At low temperatures when only surface carriers are present, a clear spin signal is observed. Moreover, the magnetic field angle dependence of the spin signal is consistent with spin–momentum locking property of surface states of SmB6.« less
  • A necessary element for the predicted topological state in Kondo insulator SmB 6 is the hybridization gap which opens in this compound at low temperatures. Here, in this work, we present a comparative study of the in-gap density of states due to Sm vacancies by Raman scattering spectroscopy and heat capacity for samples where the number of Sm vacancies is equal to or below 1%. We demonstrate that hybridization gap is very sensitive to the presence of Sm vacancies. Lastly, at the amount of vacancies above 1% the gap fills in with impurity states and low temperature heat capacity ismore » enhanced.« less