Inelastic neutron scattering study of the Kondo semiconductor<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">YbB</mml:mi></mml:mrow><mml:mrow><mml:mn>12</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Nefeodova, E. V.; Alekseev, P. A.; Mignot, J.-M.; Lazukov, V. N.; Sadikov, I. P.; Paderno, Yu. B.; Shitsevalova, N. Yu.; Eccleston, R.S.

doi:10.1103/physrevb.60.13507

Cited by 52 publications

(74 citation statements)

References 18 publications

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“…The energy of thermal neutrons is comparable to the energy scale of magnetic excitations and lattice vibrations (or phonons) in solid state materials and hence INS is ideally matched to provide vital information on magnetic exchange interactions as well as lattice dynamics. INS studies have been extensively used to understand the origin of superconductivity in Cu-based and Fe-based materials as well as unconventional superconductivity in heavy fermion materials by investigating high-and low-energy dispersive spin excitations, spin gap formation and spin resonances together with phonon dispersions [23,24,53,54]. In the present systems, CeT 2 Al 10 (T=Ru and Os), the INS technique was used to show that the single-ion CEF anisotropy is insufficient to explain the observed gapped spin wave excitations.…”

Section: Inelastic Neutron Scatteringmentioning

confidence: 99%

“…It is interesting to note that despite the spin gap opening at 45 K, CeOs 2 Al 10 exhibits long-range magnetic ordering below 29 K. Thus CeOs 2 Al 10 is a unique system and probably the first Ce-based system exhibiting a Kondo insulating gap and long-range magnetic ordering. All Kondo insulators known so far, such as CeNiSn, CeRhSb, Ce 3 Pt 3 Bi 4 , SmB 6 , YbB 6 and FeSi, are paramagnetic and do not exhibit long-range magnetic ordering down to the lowest measured temperature [20][21][22][23][24]. Furthermore in the proposed phase diagram of Fig.2, the majority of Kondo insulators are in the non-magnetic heavy fermion and mixed valence regimes of the phase diagram, but CeT 2 Al 10 (T=Ru and Os) are on the magnetic side.…”

Section: Ins Study On Polycrystalline Cet 2 a L0mentioning

confidence: 99%

“…As a consequence of strong c-f hybridization and the formation of a Kondo singlet ground state, the Kondo insulating ground state is not compatible with magnetic ordering. For example, Kondo insulators CeNiSn [20], CeRhSb [21], Ce 3 Pt 3 Bi 4 [22], SmB 6 [13,23] and YbB 12 [24] remain paramagnetic and no long range magnetic ordering has been observed in these systems. Theoretical models were proposed to explain the anisotropic properties of CeNiSn by Ikeda and Miyake (IM) based on anisotropic hybridization in k-space [25], and by Moreno and Coleman (MC) based on global and local minima in the crystal field (CEF) parameter space to explain a gap anisotropy [26].…”

Section: Introductionmentioning

confidence: 99%

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Adroja¹,

Muro²,

Takabatake³

et al. 2016

SSP

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Abstract. The recent discovery of topological Kondo insulating behaviour in strongly correlated electron systems has generated considerable interest in Kondo insulators both experimentally and theoretically. The Kondo semiconductors CeT 2 Al 10 (T=Fe, Ru and Os) possessing a c-f hybridization gap have received considerable attention recently because of the unexpected high magnetic ordering temperature of CeRu 2 Al 10 (T N =27 K) and CeOs 2 Al 10 (T N =28.5 K) and the Kondo insulating behaviour observed in the valence fluctuating compound CeFe 2 Al 10 with a paramagnetic ground state down to 50 mK. We are investigating this family of compounds, both in polycrystalline and single crystal form, using inelastic neutron scattering to understand the role of anisotropic c-f hybridization on the spin gap formation as well as on their magnetic properties. We have observed a clear sign of a spin gap in all three compounds from our polycrystalline study as well as the existence of a spin gap above the magnetic ordering temperature in T=Ru and Os. Our inelastic neutron scattering studies on single crystals of CeRu 2 Al 10 and CeOs 2 Al 10 revealed dispersive gapped spin wave excitations below T N . Analysis of the spin wave spectrum reveals the presence of strong anisotropic exchange, along the c-axis (or z-axis) stronger than in the ab-plane. These anisotropic exchange interactions force the magnetic moment to align along the c-axis, competing with the single ion crystal field anisotropy, which prefers moments along the a-axis. In the paramagnetic state (below 50 K) of the Kondo insulator CeFe 2 Al 10 , we have also observed dispersive gapped magnetic excitations which transform into quasi-elastic scattering on heating to 100 K. We will discuss the origin of the anisotropic hybridization gap in CeFe 2 Al 10 based on theoretical models of heavy-fermion semiconductors.

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Section: Inelastic Neutron Scatteringmentioning

confidence: 99%

Section: Ins Study On Polycrystalline Cet 2 a L0mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Untitled

Adroja¹,

Muro²,

Takabatake³

et al. 2016

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“…Previously [2], we have studied phonon spectra of YbB 12 and its nonmagnetic structure analogue LuB 12 on powder samples by means of INS. It was found that, owing to the small difference in mass between Yb and Lu and to the closeness in lattice constants, the phonon spectra in these compounds are quite similar.…”

Section: Phonon Density Of Statesmentioning

confidence: 99%

“…It is of particular interest because of its crystal structure formed by a rigid network of boron cuboctahedra B 12 and loosely-bound Yb ions. Inelastic neutron scattering (INS) experiments on YbB 12 have revealed that the spin-gap formation on cooling below 80 K [2,3] is also accompanied by the formation of near-gap-edge dispersive magnetic excitations [4]. The conventional approach to the Kondo-insulator problem is based on the consideration of strong f-d hybridization.…”

Section: Introductionmentioning

confidence: 99%

Lattice dynamics and magneto-elastic coupling in Kondo-insulator YbB₁₂

Rybina

Alekseev

Mignot

et al. 2007

J. Phys.: Conf. Ser.

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Abstract. Lattice dynamics and magneto-elastic coupling effects have been studied in the Kondo insulator YbB 12 by means of inelastic neutron scattering. The analysis of the phonon density of states, dispersion, and symmetry properties is presented in connection with a possible magneto-elastic coupling. Manifestation of such effects was found for the phonons corresponding to the vibrations of Yb atoms. IntroductionKondo-insulators form a specific class of the rare-earth compounds which behave as Kondo metals at room temperature and transform to narrow-gap semiconductors with a non-magnetic ground state on decreasing temperature [1]. YbB 12 is a typical Kondo-insulator and the only example reported so far among Yb-based compounds. It is of particular interest because of its crystal structure formed by a rigid network of boron cuboctahedra B 12 and loosely-bound Yb ions. Inelastic neutron scattering (INS) experiments on YbB 12 have revealed that the spin-gap formation on cooling below 80 K [2,3] is also accompanied by the formation of near-gap-edge dispersive magnetic excitations [4]. The conventional approach to the Kondo-insulator problem is based on the consideration of strong f-d hybridization. However one should not exclude the possible interplay between electron and lattice excitations, at least in case of YbB 12 where collective magnetic excitations (characteristic for the low-temperature Kondo-insulating regime) fall in the same energy range as phonons associated with rare-earth ion vibrations. Since the structure of the magnetic excitation spectrum itself is strongly temperaturedependent such magneto-elastic coupling (MEC) effects can become especially evident when studying the temperature evolution of phonon spectra.In this paper we present the results of an INS study of the phonon density of states (PhDOS) and dispersion curves in YbB 12 (partly published in [5,6]), along with possible evidence for MEC effects.

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