論文の公開元へAnomalous electron hydrodynamics in noncentrosymmetric materials
概要
Recent remarkable developments of experimental techniques, such as microfabrication and
quantum sensing with diamond nitrogen-vacancy centers, have opened up a new nonequilibrium regime of electronic dynamics in solids, dubbed the hydrodynamic regime.
It is believed to be realized in clean metals/semiconductors with high conductivity and
strong electronic correlations, where the electronic dynamics is described in the framework
of electron hydrodynamics. Interestingly, in the novel regime, electron systems exhibit a
variety of fascinating and unconventional transport phenomena, such as the Gurzhi effect,
negative nonlocal resistance, preturblent-induced current fluctuation, and negative magnetoresistance. Since these phenomena originate from the nonlocality due to the electron
viscosity and the nonlinearlity of the fluid dynamics, they are considered to characterize
electron dynamics in the hydrodynamic regime.
In recent years, hydrodynamic signatures mentioned above have been confirmed through
transport experiments in various clean materials, including GaAs quantum wells, 2D monovalent layered metal PdCoO2 , monolayer/bilayer graphene, and Weyl semimetal WP2 .
Furthermore, because the hydrodynamic approach gives us clear and intuitive understading of the cross-interaction between various quasiparticles, such as magnons and phonons,
and nonlocal/nonlinear optical response, its applications to the field of spintronics and
plasmonics has also begun to be discussed. For these reasons, electron hydrodynamics has
been attracting much interest in recent years and is quickly growing into a mature field of
condensed matter physics.
More recently, symmetry of crystals and quantum geometry give a new twist to the
concept of electron hydrodynamics. These aspects are irrelavant to usual fluids such as
water, and thus clearly highlight the difference between electron fluids in crystals and
conventional fluids. In fact, enthusiastic researches in the last few years have clarified rich
and novel hydrodynamic phenomena, such as anisotropic viscosity effects and anomalous
collective modes.
In this thesis, we focus on electron fluids in noncentrosymmetric crystals and clarify a
variety of hydrodynamic phenomena peculiar to the systems. Our main purpose in this
thesis can be summarized as follows:
1. Formulation of an electron hydrodynamic theory in noncentrosymmetric
crystals.
2. Proposal of novel hydrodynamic phenomena peculiar to noncentrosymmetric systems and observables with existing experimental technologies.
3. Application of the obtained hydrodynamic theories to novel plasmonic
devices. ...
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