Integrated Plasmonics: Broadband Dirac Plasmons in Borophene

The over-tilting of type-II Dirac cones has led to various fascinating quantum phenomena. Here we find two anomalous acoustic plasmons (AAPs) are dictated by the distinct geometry of two-dimensional (2D) type-II Dirac cones, far beyond the conventional $\text{\ensuremath{\sqrt{q}}}$ plasmon. One AAP originates from the strong hybridization of two pockets at one Dirac point, whereas the other is attributed to the significant enhancement of the band correlation around the open ...

Two-dimensional materials support deeply confined and tunable plasmonic modes, which have great potential for achieving device miniaturization and flexible manipulation. In this paper, we propose a diffraction-unlimited system composed of borophene layer and perovskite grating to investigate the strong coupling between the borophene guiding plasmon (BGP) and perovskite exciton (PE) mode. The resonant energy of BGP mode could be electrically tuned to match the energy of PE mod...

Light-matter interaction in two-dimension photonic materials allows for confinement and control of free-space radiation on sub-wavelength scales. Most notably, the van der Waals heterostructure obtained by stacking graphene (G) and hexagonal Boron Nitride (hBN) can provide for hybrid hyperbolic plasmon phonon-polaritons (HP3). Here, we present a polariton diode effect and low-bias control of HP3 modes confined in G-hBN. Using broadband infrared synchrotron radiation coupled t...

Among a huge variety of known two-dimensional materials, some of them have anisotropic crystal structures; examples include so different systems as a few-layer black phoshphorus (phosphorene), beryllium nitride BeN$_4$, van der Waals magnet CrSBr, rhenium dichalgogenides ReX$_2$. As a consequence, their optical and electronic properties turn out to be highly anisotropic as well. In some cases, the anisotropy results not just in a smooth renormalization of observable propertie...

Two-dimensional boron sheets (borophenes) have been successfully synthesized in experiments and are expected to exhibit intriguing transport properties such as the emergence of superconductivity and Dirac Fermions. However, quantitative understanding of intrinsic electrical transport of borophene has not been achieved. Here, we report a comprehensive first-principles study on electron-phonon driven intrinsic electrical resistivity (\r{ho}) of emerging borophene structures. We...

We consider theoretically, using the random phase approximation (RPA), low-energy intrinsic plasmons for two-dimensional (2D) systems obeying Dirac-like linear chiral dispersion with the chemical potential set precisely at the charge neutral Dirac point. The "intrinsic Dirac plasmon" energy has the characteristic $q^{1/2}$ dispersion in the 2D wave-vector $q$, but vanishes as $T^{1/2}$ in temperature for both monolayer and bilayer graphene. The intrinsic plasmon becomes overd...

In recent years, two-dimensional boron sheets (borophene) have been experimentally synthesized and theoretically observed as promising conductor or transistor with novel thermal and electronic properties. We first give a general survey of some notable electronic properties of borophene, including the superconductivity and topological characters. We then mainly review the basic approaches, thermal transport, as well as the mechanical properties of borophene with different conf...

Graphene is a valuable 2D platform for plasmonics as illustrated in recent THz and mid-infrared optics experiments. These high-energy plasmons however, couple to the dielectric surface modes giving rise to hybrid plasmon-polariton excitations. Ultra-long-wavelengthes address the low energy end of the plasmon spectrum, in the GHz-THz electronic domain, where intrinsic graphene Dirac plasmons are essentially decoupled from their environment. However experiments are elusive due ...

Two rich and vibrant fields of investigation, graphene physics and plasmonics, strongly overlap. Not only does graphene possess intrinsic plasmons that are tunable and adjustable, but a combination of graphene with noble-metal nanostructures promises a variety of exciting applications for conventional plasmonics. The versatility of graphene means that graphene-based plasmonics may enable the manufacture of novel optical devices working in different frequency ranges, from tera...

Recently, the crystal symmetry-protected topological semimetals have aroused extensive interests, especially for the nonsymmorphic symmetry-protected one. We list the possible nonmagnetic topological semimetals and develop their k.p Hamiltonian in all layer groups with multiple screw axes in the absence of spin-orbital coupling. We find a novel cat's cradle-like topological semimetal phase, which looks like multiple hourglass-like band structures staggered together. Furthermo...