Voltage switching of a VO2 memory metasurface using ionic gel

Abstract

We demonstrate an electrolyte-based voltage tunable vanadium dioxide (VO2) memory metasurface. Large spatial scale, low voltage, non-volatile switching of terahertz (THz) metasurface resonances is achieved through voltage application using an ionic gel to drive the insulator-to-metal transition in an underlying VO2 layer. Positive and negative voltage application can selectively tune the metasurface resonance into the “off” or “on” state by pushing the VO2 into a more conductive or insulating regime respectively. Compared to graphene based control devices, the relatively long saturation time of resonance modification in VO2 based devices suggests that this voltage-induced switching originates primarily from electrochemical effects related to oxygen migration across the electrolyte–VO2 interface.

Tunable and low-loss correlated plasmons in Mott-like insulating oxides

“…The correlated plasmons of hp-SNO are fundamentally different from conventional (bulk) plasmon in lp-SNO, conventional metals such as gold3526 and the metallic phases of strongly correlated materials such as metallic V O 2 (refs 6, 7, 8) for the following reasons. First, since hp-SNO is insulator-like, the correlated plasmons do not originate from collective excitations of free charges.…”

“…In strongly-correlated materials, conventional forms of plasmons have been observed in the metallic or superconducting phases of these materials, and there have been studies to explore their potential for plasmonics in vanadium oxides678 and cuprates910. In particular, localized conventional surface plasmons have been observed in the metallic phase of V O 2 , and its temperature-dependent metal–insulator transition has been utilized for plasmonic switching and sensing678.…”

“…In particular, localized conventional surface plasmons have been observed in the metallic phase of V O 2 , and its temperature-dependent metal–insulator transition has been utilized for plasmonic switching and sensing678. However, in strongly-correlated, insulating phases of these materials (such as in Mott insulators11), correlated forms of plasmons under long-range Coulomb interactions have only been theoretically investigated12 but not experimentally observed.…”

A review of metasurfaces: physics and applications

“…Vanadium dioxides (VO 2 ) is another thermally driven insulator-to-metal phase transition material that has attracted great interest in realizing thermally active metasurfaces at THz and infrared frequencies [200][201][202][203][204][205]. The nonvolatile thermally switchable metasurface response has potential applications such as memory devices [201], and the metasurface resonance can be also switched through the application of a voltage bias [198]. In the latter case, a thin layer of ionic gel was applied on the surface of the metasurface ( figure 29(a)).…”

“…Insets: photos of the gold SRR sitting on VO 2 before the ionic gel is applied. Used with permission from [198]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 voltages monotonically damps the SRR resonance, with 3 volts yielding complete suppression of the resonance ( figure 29(c)).…”