Theory of Spin Exciton in the Kondo Semiconductor $Yb{B}_{12}$

Abstract

The Kondo semiconductor $Yb{B}_{12}$ exhibits a spin and charge gap of approximately 15 meV. Close to the gap energy narrow dispersive collective excitations were identified by previous inelastic neutron scattering experiments. We present a theoretical analysis of these excitations. Starting from a periodic Anderson model for crystalline electric field (CEF) split 4f states we derive the hybridized quasiparticle bands in slave boson mean-field approximation and calculate the momentum dependent dynamical susceptibility in random phase approximation (RPA). We show that a small difference in the hybridization of the two CEF (quasi-) quartets leads to the appearance of two dispersive spin resonance excitations at the continuum threshold. Their intensity is largest at the antiferromagnetic (AF) zone boundary point and they have an upward dispersion which merges with the continuum less than halfway into the Brillouin zone. Our theoretical analysis explains the most salient features of previously unexplained experiments on the magnetic excitations of $Yb{B}_{12}$.

5 pages, 4 figures, To be published in Physical Review Letters

References in corpus (1)

• Feedback spin resonance in superconducting CeCu${}_2$Si${}_2$ and CeCoIn${}_5$

Cited by in corpus (5)

• Spin Exciton Formation inside the Hidden Order Phase of CeB6
• Hall anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB${}_{12}$: Evidence for Unconventional Charge Transport
• Field induced spin exciton doublet splitting in d_{x^2-y^2}-wave 115-heavy electron superconductors
• Crystal field potential and short-range order effects in inelastic neutron scattering, magnetization and heat capacity of the cage-glass compound HoB12
• Crystalline electric field excitations in Weyl semimetal \textit{R}AlSi (\textit{R} = Ce, Pr and Nd)