Infrared plasmons in ultrahigh conductive PdCoO2 metallic oxide

Abstract

PdCoO2 layered delafossite is the most conductive compound among metallic oxides, with a room-temperature resistivity of nearly $$2\,\mu \Omega \,{{{{{\rm{cm}}}}}}$$ 2 μ Ω cm , corresponding to a mean free path of about 600 Å. These values represent a record considering that the charge density of PdCoO2 is three times lower than copper. Although its notable electronic transport properties, PdCoO2 collective charge density modes (i.e. surface plasmons) have never been investigated, at least to our knowledge. In this paper, we study surface plasmons in high-quality PdCoO2 thin films, patterned in the form of micro-ribbon arrays. By changing their width W and period 2W, we select suitable values of the plasmon wavevector q, experimentally sampling the surface plasmon dispersion in the mid-infrared electromagnetic region. Near the ribbon edge, we observe a strong field enhancement due to the plasmon confinement, indicating PdCoO2 as a promising infrared plasmonic material.

Generation of Terahertz Radiation via the Transverse Thermoelectric Effect

“…Additionally, the significant discrepancy in characteristic length scales between our system (20 nm) and a study on surface plasmons (200 nm), assuming a linear relation between wavevector and plasma frequency, further supports the exclusion of surface field effects as the primary cause of THz emission in our specific case. [32,40] To foster the TTE origin of the THz generation, we also conduct sample orientation-dependent measurements under normal incidence as shown in Figure 2a,b. For the thermoelectric origin of the THz emission, a 𝜑 = 180°rotation of the sample around the surface normal ⃗ n, switches the sign of the polarity of the measured field E THz .…”

“…Additionally, the significant discrepancy in characteristic length scales between our system (20 nm) and a study on surface plasmons (200 nm), assuming a linear relation between wavevector and plasma frequency, further supports the exclusion of surface field effects as the primary cause of THz emission in our specific case. [ 32,40 ]…”

Extraordinary optical transmittance generation on Si3N4 membranes

“…[19][20][21] Even noble metals, such as silver and gold, are scarcely efficient in this spectral range, which strongly affects the realization of such applications. Although the use of unconventional materials like graphene, [22][23][24][25] topological insulators, 26 and high temperature superconductors 27,28 may mitigate this effect, an alternative way to obtain efficient field confinement and enhancement at IR frequencies consists in exploiting another kind of collective excitation: the surface phonon polariton (SPhP). 29 Using polar dielectric materials, a coupling between electromagnetic radiation and optical phonons at infrared frequencies can be obtained in a way similar to both propagating and localized surface plasmons in metals.…”

Terahertz Resonators based on Y-Ba-Cu-O High-Tc Superconductor

“…Indeed, thanks to specific patterning, the optical response of these systems can be engineered with respect to the original material, paving the way to innovative opto-electronic applications. The most widely spread MMs are constituted of periodically patterned thin metallic films deposited on a dielectric substrate, enabling to trigger unusual electromagnetic properties, ranging from superlenses [10], sensors [11,12], light induced transparency [13], chiral devices [14], filters [15], and modulators [16]. However, two main issues limit the practical applications of metallic metamaterial devices: Ohmic losses and tunability.…”