Optical Pump-Probe and Transient Grating Study of SmB6

ORAL

Abstract

We study ultrafast quasiparticle (QP) relaxation and diffusion dynamics in Al flux-grown SmB6 single crystals using optical pump-probe (OPPS) and transient grating (TGS) spectroscopies. OPPS is sensitive to small gaps in the density of states near the Fermi energy due to the relaxation bottleneck effect. TGS, a variant of OPPS in which two pump pulses are interfered on the sample surface to create a spatially periodic excitation, yields additional information, including the optical phases and diffusion constants associated with photoexcited QPs. SmB6 is a mixed valence compound that becomes a Kondo Insulator when a hybridization gap opens near 50 K. At low temperatures, anomalous behavior is observed with a variety of experimental techniques. Past OPPS results on SmB6 show changes in the QP relaxation dynamics in the low temperature phase1,2. Using TGS, we measure relaxation and diffusion dynamics of QPs as a function of pump excitation density, crystal surface, and probe wavelength, from room temperature to 3.3 K, in an attempt to clarify the origin of the anomalous low temperature OPP signal reported in previous studies.
[1] Demsar, J. et al., Phys. Rev. Lett. 96, 037401 (2006).
[2] Adhikari, S. et al., arXiv:1502.04441v2 (2015).

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Presenters

  • Peter Kissin

    Physics, Univ of California - San Diego, Univ of California - San Diego, Physics, University of California, San Diego

Authors

  • Peter Kissin

    Physics, Univ of California - San Diego, Univ of California - San Diego, Physics, University of California, San Diego

  • Monica Ciomaga Hatnean

    Physics, University of Warwick, University of Warwick

  • Guangwu Duan

    Mechanical Engineering, Boston University, Department of Mechanical Engineering, Boston University, Boston University, Boston Univ

  • Xin Zhang

    Mechanical Engineering, Boston University, Department of Mechanical Engineering, Boston University, Boston University, Boston Univ

  • Geetha Balakrishnan

    Department of Physics, University of Warwick, Physics, University of Warwick, University of Warwick

  • Richard Averitt

    Physics, University of California, San Diego, Physics, Univ of California - San Diego, Univ of California - San Diego, Department of Physics, University of California San Diego, Department of Physics, Univ of California - San Diego, University of California San Diego