Magnetoplasmons in monolayer black phosphorus structures

Abstract

Two-dimensional materials supporting deep-subwavelength plasmonic modes can also exhibit strong magnetooptical responses. Here, we theoretically investigate magnetoplasmons (MPs) in monolayer black phosphorus (BP) structures under moderate static magnetic fields. We consider three different structures, namely, a continuous BP monolayer, an edge formed by a semi-infinite sheet, and finally, a triangular wedge configuration. Each of these structures shows strongly anisotropic magneto-optical responses induced both by the external magnetic field and by the intrinsic anisotropy of the BP lattice. Starting from the magneto-optical conductivity of a single-layer of BP, we derive the dispersion relation of the MPs in the considered geometries, using a combination of analytical, semi-analytical, and numerical methods. We fully characterize the MP dispersions and the properties of the corresponding field distributions, and we show that these structures sustain strongly anisotropic subwavelength modes that are highly tunable. Our results demonstrate that MPs in monolayer BP, with its inherent lattice anisotropy as well as magnetically induced anisotropy, hold potential for tunable anisotropic materials operating below the diffraction limit, thereby paving the way for tailored nanophotonic devices at the nanoscale.

Tunable Optical Properties of 2D Materials and Their Applications

“…The results showed MPs in monolayer BP bear a great probability for tunable anisotropic materials under the diffraction limit operation. [ 167 ] To better enhance Faraday rotation angle while keeping high transmittance, Dong et al. presented a theoretical study on the integration of single‐layer phosphorus with a symmetric 1D defective magnetophotonic crystal.…”

“…The results showed MPs in monolayer BP bear a great probability for tunable anisotropic materials under the diffraction limit operation. [167] To better enhance Faraday rotation angle while keeping high transmittance, Dong et al presented a theoretical study on the integration of single-layer phosphorus with a symmetric 1D defective magnetophotonic crystal. The experiment results demonstrated that the Faraday rotation angle was intensively enhanced since the defect mode of the magnetophotonic crystal can intensively confine the electromagnetic field near the BP.…”

Unidirectional-propagating surface magnetoplasmon based on remanence and its application for subwavelength isolators

“…Noble metals and semiconductors usually lose their gyroelectric properties when the external magnetic field is turned off, and the related permittivity tensor reduces to a scalar. Two-dimensional materials, such as graphene and black phosphorus, also lose their gyroelectric properties after removing the external magnetic field [13][14][15]. However, ferrimagnetic material with remanence still preserves its gyromagnetic property after removing the external magnetic field, and its permeability has the tensor form:…”

“…Realization of one-way electromagnetic mode generally relies on magneto-optical materials and strong external magnetic field. Recent researches have also shown that two-dimensional (2D) materials can support MPs of topologically protected optical states [13][14][15]. Though one-way MPs in such magneto-optical materials, from three-dimensional (3D) metals and doped semiconductors to two-dimensional graphene and black phosphorus, exhibit many alluring properties, the requirement of external magnetic field seriously hinders the miniaturization and integration of related optical devices.…”

Theory for optical activity in monolayer black phosphorus under external magnetic field

“…Very recently, researches numerically demonstrated that strong a e-mail: yinchengping1979@163.com optical activity can be realized in a monolayer black phosphorus (BP) [31]. As a kind of two-dimensional materials, monolayer BP has a puckered crystal structure of phosphorus atoms, which gives rise to an in-plane anisotropy with different electron (or hole) effective masses along armchair (AC) and zigzag (ZZ) directions [32]. The optical activity obtained in reference [31] can be attributed to the extrinsic chirality from the mutual orientation of the monolayer BP with in-plane anisotropy and the incident light wave.…”