Terahertz magnetoplasmon resonances in coupled cavities formed in a gated two-dimensional electron gas

Abstract

We report on both experiments and theory of low-terahertz frequency range (up to 400 GHz) magnetoplasmons in a gated two-dimensional electron gas at low (<4K) temperatures. The evolution of magnetoplasmon resonances was observed as a function of magnetic field at frequencies up to ∼400 GHz. Full-wave 3D simulations of the system predicted the spatial distribution of plasmon modes in the 2D channel, along with their frequency response, allowing us to distinguish those resonances caused by bulk and edge magnetoplasmons in the experiments. Our methodology is anticipated to be applicable to the low temperature (<4K) on-chip terahertz measurements of a wide range of other low-dimensional mesoscopic systems.

Effect of mesa geometry on low-terahertz frequency range plasmons in two-dimensional electron systems

“…In addition, we approximated the frequency content of the excitation pulses by assuming that the excitation amplitude decays exponentially with frequency f , as exp(−7.5f × 10 −12 ) [49]. For the rectangular device, compared to our previous experiments [33], we were able to observe more resonances, owing to shortened ungated portions of the channel that leads to smaller propagation loss. Seven resonances were observed, (see figure 7(a)), although those at higher frequencies are weak (owing to the decay of the excitation signal).…”

“…Figures 1(c) and (d) show their micrographs. Fabrication and measurements followed the procedure detailed elsewhere [31,32,33]. The rectangular device comprised an 18.8-µm-long rectangular mesa.…”

Enhanced Terahertz Spectral‐Fingerprint Detection of α‐Lactose Using Sub‐Micrometer‐Gap On‐Chip Waveguides

“…Figure a shows a schematic of a CPW undergoing THz transmission coupled to a lactose block loaded the CPW from above and whose properties are directly sensed by the evanescent field in the waveguide. The center conductor of the CPW was defined with center conductor widths in the range of 750 nm – 30 µm, with a metal thickness of 150 nm, [ 14–16 ] a length of 150 µm, and was given slot gap widths ( w slot ) in the range of 0.5–20 µm between the center conductor and the neighboring ground planes. An α‐lactose block with a thickness of h lactose , a width of 120 µm, and length of 50 µm was used as the exemplar target material.…”

“…CPW is a well‐known high frequency transmission line consisting of a three‐conductor structure comprising two ground planes separated by a gap on either side of a signal conductor [ 14,15 ] which has been widely adopted in on‐chip THz systems. THz waves propagate along the slot gap with a well‐confined electric field that can nonetheless interact with adjacent small systems such as 2D electron gas channels, for example.…”

“…THz waves propagate along the slot gap with a well‐confined electric field that can nonetheless interact with adjacent small systems such as 2D electron gas channels, for example. [ 14,15 ] We previously reported a giant magnetoresistance in a tapered sub‐micrometer‐gapped CPW structure formed from a magnetic multilayer. [ 16 ] The area of electric field confinement in the slot gap decreased as the CPW was tapered down to ≈0.5 µm, while the associated magnitude of the electric field increased.…”