Agradecimentos: This work was supported by the auspices of FAPESP (Grant Nos. 2011/01564-0, 2012/04870-7, 2012/05903-6, 2011/19924-2, 2013/17427-7), CNPq, FINEP and CAPES (Brazil). ZF is supported by the US NSF (Grant No. DMR-0801253) and PS by the US DOE (Grant No. DE-FG02-98ER45707). Work at Los...

Agradecimentos: This work was supported by the auspices of FAPESP (Grant Nos. 2011/01564-0, 2012/04870-7, 2012/05903-6, 2011/19924-2, 2013/17427-7), CNPq, FINEP and CAPES (Brazil). ZF is supported by the US NSF (Grant No. DMR-0801253) and PS by the US DOE (Grant No. DE-FG02-98ER45707). Work at Los Alamos National Laboratory (LANL) was performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering. PFSR acknowledges a Director's Postdoctoral Fellowship through the LANL LDRD program

Abstract: 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 G8 quartet with a nearby G6 excited doublet. The angular dependence of the resonances is not consistent with...

Abstract: 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 G8 quartet with a nearby G6 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 G3 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

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP

2011/01564-0; 2011/19924-2; 2012/04870-7; 2012/05903-6; 2013/17427-7

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ

FINANCIADORA DE ESTUDOS E PROJETOS - FINEP

COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES

Aberto