|연사||Dr. Ji Hun Sim (POSTECH)|
Dynamical mean field theory studies on heavy fermion system
Dec. 11 (Fri.), 15:45 PM, E6-2. 1st fl. #1323
Dr. Ji Hun Sim, POSTECH
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] Under the pressure or chemical doping, the temperature scale can be changed which is related to the movement of the quantum critical point.[3,4] 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  and suggest that the CEF effect enhances the localization of the Yb ions under pressure. We will also discuss the temperature evolution of Kondo resonance band observed in topological Kondo insulator such as SmB6 and YbB6.
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 H. C. Choi et al, Phys. Rev. B, 88, 125111 (2013).
 J. H. Shim et al, Science 318, 1615 (2007).
 S. Seo et al, Nat. Commun. 6, 6433 (2015).
 S. Ernst et al., Nature (London) 474, 362 (2011).
 O. Trovarelli et al., Phys. Rev. Lett. 85, 626 (2000).
 J. Denlinger et al., arXiv:1312.6637
Contact: Heung Sun Sim, Physics Dept., (firstname.lastname@example.org)