Yb-Yb correlations and crystal-field effects in the Kondo insulator YbB12 and its solid solutions

Abstract

We have studied the effect of Lu substitution on the spin dynamics of the Kondo insulator YbB12 to clarify the origin of the spin-gap response previously observed at low temperature in this material. Inelastic neutron spectra have been measured in Yb1-xLuxB12 compounds for four Lu concentrations x = 0, 0.25, 0.90 and 1.0. The data indicate that the disruption of coherence on the Yb sublattice primarily affects the narrow peak structure occurring near 15-20 meV in pure YbB12, whereas the spin gap and the broad magnetic signal around 38 meV remain almost unaffected. It is inferred that the latter features reflect mainly local, single-site processes, and may be reminiscent of the inelastic magnetic response reported for mixed-valence intermetallic compounds. On the other hand, the lower component at 15 meV is most likely due to dynamic short-range magnetic correlations. The crystal-field splitting in YbB12 estimated from the Er3+ transitions measured in a Yb0.9Er0.1B12 sample, has the same order of magnitude as other relevant energy scales of the system and is thus likely to play a role in the form of the magnetic spectral response.

16 pages in pdf format, 9 figures. v. 2: coauthor list updated; extra details given in section 3.2 (pp. 6-7); one reference added; fig. 5 axis label changed

References in corpus (4)

• Optical conductivity of the Kondo insulator YbB_12: Gap formation and low-energy excitations
• Dynamics and transport properties of Kondo insulators
• Interplay between Heavy Fermions and Crystal Field Excitation in Kondo Lattices. Low-Temperature Thermodynamics and Inelastic Neutron Scattering Spectra of CeNiSn
• Short-range antiferromagnetic correlations in Kondo insulators

Cited by in corpus (7)

• Evidence for short-range antiferromagnetic fluctuations in Kondo-insulating YbB12
• Theory of Spin Exciton in the Kondo Semiconductor $Yb{B}_{12}$
• Hybridization gap formation in the Kondo insulator YbB${}_{12}$ observed using time-resolved photoemission spectroscopy
• Crystal field potential and short-range order effects in inelastic neutron scattering, magnetization and heat capacity of the cage-glass compound HoB12
• Heavy quasiparticle bands in the underscreened quasiquartet Kondo lattice
• Singlet-triplet Hamiltonian for spin excitation in the Kondo-insulator
• Optical and magnetic excitations in the underscreened quasi-quartet Kondo lattice