Condensed Matter/Biological Physics Seminar: Dr. Ji Hoon Shim, Pohang University of Science and Technology  Add To Calendar

  • Date(s): Friday, 6/5 2:00 PM to Friday, 6/5 3:00 PM
  • Speaker: Dr. Ji Hoon Shim
  • Host: Hyowon Park
  • Campus Address: 2214 SES (Science and Engineering South)

Title: Evolution of heavy fermion under temperature and pressure changes in heavy fermion compounds and topological Kondo insulators
 
Abstract: 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 [5] and suggest that the CEF effect enhances the localization of the Yb ions under pressure.[6] We will also discuss the temperature evolution of Kondo resonance band observed in topological Kondo insulator such as SmB6 and YbB6.[7]

 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] J. H. Shim et al, Science 318, 1615 (2007).

[4] S. Seo et al, Nat. Commun. 6, 6433 (2015).

[5] S. Ernst et al., Nature (London)  474, 362 (2011).

[6] O. Trovarelli et al., Phys. Rev. Lett. 85, 626 (2000).

[7] J. Denlinger et al., arXiv:1312.6637

Cm-Bio 6-5 Shim