"HYPERBOLIC ELECTRODYNAMICS OF ANISOTROPIC QUANTUM MATERIALS"

By Dmitri N.Basov (Columbia University, New York, USA)

BIOGRAPHY:

Dmitri N. Basov (PhD 1991) is a Higgins professor and Chair of the Department of Physics at Columbia University [http://infrared.cni.columbia.edu], the Director of the DOE Energy Frontiers Research Center on Programmable Quantum Materials and co-director of Max Planck Society – New York Center for Nonequilibrium Quantum Phenomena. He has served as a professor (1997-2016) and Chair (2010-2015) of Physics, University of California San Diego. Research interests include: physics of quantum materials, superconductivity, two-dimensional materials, infrared nano-optics. Prizes and recognitions: Sloan Fellowship (1999), Genzel Prize (2014), Humboldt research award (2009), Frank Isakson Prize, American Physical Society (2012), Moore Investigator (2014, 2020), K.J. Button Prize (2019), Vannevar Bush Faculty Fellowship (U.S. Department of Defense, 2019), National Academy of Sciences (2020). 

ABSTRACT:

Common materials bounce light as the real part of the dielectric function () becomes negative. Perhaps counterintuitively, anisotropic layered crystals do support propagating modes provided in-plane and out-of-plane dielectric functions are of the opposite sign (). Because the relevant isofrequency surface is the hyperboloid such media are referred to as hyperbolic. In the hyperbolic regime, the interaction of light with collective modes of crystals yields hyperbolic polaritons with exotic properties, including ray-like waveguiding in the bulk. Such waveguiding was mostly explored in polar insulators inside narrow phonon Reststrahlen bands. Hyperbolic waveguiding is anticipated in a wide variety of anisotropic conductors as well. Anisotropic semiconductors and metals, in principle, offer broadband hyperbolicity. However, the inherently strong electronic loss prevents waveguiding of infrared modes. I will discuss recent nano-optical experiments by Shao et al. who discovered hyperbolic waveguiding in anisotropic nodal semi-metal ZrSiSe [1]. Nodal band structure and attendant van Hove singularities dramatically enhance plasmonic response while simultaneously reducing interband losses to the level required to observe propagating hyperbolic plasmon polaritons (HPP) in infrared. I will also discuss experiments by Sternbach et al. who discovered non-equilibrium hyperbolic polaritons in a layered semiconductor WSe2 prompted by femto-second optical pumping and rooted in exciton dynamics [2]

REFERENCE(S):

1.Yinming Shao, Aaron J. Sternbach, Brian S. Y. Kim, Andrey A. Rikhter, Xinyi Xu, Umberto De Giovannini, Ran Jing, Sang Hoon Chae, Zhiyuan Sun, Seng Huat Lee, Yanglin Zhu, Zhiqiang Mao, J. Hone, Raquel Queiroz, A. J. Millis, P. James Schuck, A. Rubio, M. M. Fogler, D. N. Basov “Infrared Plasmons Propagate through a Hyperbolic Nodal Metal” (to be published).

2. A. J. Sternbach, S. H. Chae, S. Latini, A. A. Rikhter, Y. Shao, B. Li, D. Rhodes, B. Kim, J. Schuck, X. Xu, X.-Y. Zhu, R. D. Averitt, J. Hone, M. M. Fogler, A. Rubio, and D. N. Basov, “Programmable hyperbolic polaritons in van der Waals semiconductors,” Science 371, 617 (2021).