Evolution of heavy fermion under temperature and pressure changes in heavy fermion compounds and topological Kondo insulator

Ji Hoon Shim,
Department of Chemistry & Physics, Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea


In f electron-based heavy fermion compounds, the temperature dependent behavior of the f electron is determined by the competition between Kondo effect and RKKY interaction. The f electron's magnetic moments bind to the itinerant quasiparticles to form composite heavy quasiparticle bands at low temperature to produce a large Fermi surface. When the f electrons are localized free moments, a small Fermi surface is induced with the absence of coherent contribution from f electrons. In the dynamical mean field theory approach of Ce-based heavy fermion compounds, we addressed that the Fermi surface sizes and their effective masses show continuous logarithmic scaling behavior (~ ln(T0/T)) with different characteristic temperatures.[1,2] Also, the role of crystalline electric field (CEF) to the spectral function has been investigated in YbRh2Si2 with well-defined CEF splitting. We describe the CEF multiplet Kondo resonance peaks similar to recent experimental observation [3] and suggest that the CEF effect enhances the localization of the Yb ions under pressure.[4] We will also discuss the temperature evolution of Kondo resonance band observed in topological Kondo insulator such as SmB6 and YbB6.[5]

References:
[1] H. C. Choi et al, Phys. Rev. Lett., 108, 016402 (2012).
[2] H. C. Choi et al, Phys. Rev. B, 88, 125111 (2013).
[3] S. Ernst et al., Nature (London) 474, 362 (2011).
[4] O. Trovarelli et al., Phys. Rev. Lett. 85, 626 (2000).
[5] J. Denlinger et al., arXiv:1312.6637