A Vanadium Dioxide Metamaterial Disengaged from Insulator-to-Metal Transition

Abstract

We report that vanadium dioxide films patterned with λ/100000 nanogaps exhibit an anomalous transition behavior at millimeter wavelengths. Most of the hybrid structure's switching actions occur well below the insulator to metal transition temperature, starting from 25 °C, so that the hysteresis curves completely separate themselves from their bare film counterparts. It is found that thermally excited intrinsic carriers are responsible for this behavior by introducing enough loss in the context of the radically modified electromagnetic environment in the vicinity of the nanogaps. This phenomenon newly extends the versatility of insulator to metal transition devices to encompass their semiconductor properties.

Hybrid metamaterials for electrically triggered multifunctional control

“…Consequently, in optics, various approaches to the realization of active nanophotonic systems have been explored and can be roughly classified by the means to which the refractive index can be tuned, including from the intrinsic birefringence of materials that exhibit a large electro-optic coefficient, for example, liquid crystals131415, and ferroelectric materials such as barium titanate (BaTiO 3 )16, from the carrier excitations in semiconductors such as Silicon1718, quantum dots such as CdSe quantum dots19, and graphene2021 as well as from the transition of phase change materials22232425262728293031323334353637. Moreover, in accordance with the Clausius–Mossotti relation, the change in refractive index arises by varying the polarizability α , albeit by different mechanisms.…”

“…In light of this, vanadium dioxide (VO 2 ), a classical transition metal oxide that behaves as an insulator (monoclinic phase) and half-filled metal (3 d 1 , ( S =1/2), tetragonal phase) at temperatures below and above the insulator-to-metal transition (IMT) temperature ( T IMT ∼67 °C in bulk crystals)38, respectively, has been used to facilitate tunable metamaterials. In these systems the IMT of VO 2 has been achieved through either direct thermal control23242526272831323334 or by the resonance-enhanced opto-thermal effect3035. A detailed analysis of the VO 2 -based metadevices that have been reported on to date can be found in Supplementary Table 1 and Supplementary Note 6.…”

Dynamic Terahertz Plasmonics Enabled by Phase‐Change Materials

“…[60,[65][66][67][68][69][70][71][72][73] As an example, active full control of THz transmission with enhanced switching efficiency during the thermal IMT has been demonstrated on a 100 nm thick VO 2 film combined with an array of rectangular slot-type gold nanoantennas (Figure 2a). Although thermal heating is not a perfect method in terms of being fast and enabling precise control, it is still stable and useful for investigating the overall IMT process without any complicated system.…”

“…[65] Stronger separation can Young-Gyun Jeong received his Ph.D. in physics from the Seoul National University in 2014. [65] Stronger separation can Young-Gyun Jeong received his Ph.D. in physics from the Seoul National University in 2014.…”

Flat Helical Nanosieves

“…Examples include optical vortex plate, [6] ultrathin flat lens, [7][8][9][10] propagating wave to surface wave convertor, [11,12] broadband quarter-wave plate, [13] directional surface plasmon polaritons excitation, [14] and meta-hologram. [15][16][17][18][19][20] Especially for the Pancharatnam-Berry (PB) metasurface, [21] it transfers the interfacial phase distribution into orientations of base units, which largely simplifies the design process of optical antenna compared with those metasurfaces based on spatially varying geometric parameters (e.g., V-shaped metasurface, slot antenna array metasurface [22][23][24] ). Thus, metasurface provides new opportunities and strategies to develop ultrathin optical devices that are compatible with integrated and compact systems.…”