2 research outputs found
Quantum Control of Graphene Plasmon Excitation and Propagation at Heaviside Potential Steps
Quantum
mechanical effects of single particles can affect the collective
plasmon behaviors substantially. In this work, the quantum control
of plasmon excitation and propagation in graphene is demonstrated
by adopting the variable quantum transmission of carriers at Heaviside
potential steps as a tuning knob. First, the plasmon reflection is
revealed to be tunable within a broad range by varying the ratio Îł
between the carrier energy and potential height, which originates
from the quantum mechanical effect of carrier propagation at potential
steps. Moreover, the plasmon excitation by free-space photos can be
regulated from fully suppressed to fully launched in graphene potential
wells also through adjusting Îł, which defines the degrees of
the carrier confinement in the potential wells. These discovered quantum
plasmon effects offer a unified quantum-mechanical solution toward
ultimate control of both plasmon launching and propagating, which
are indispensable processes in building plasmon circuitry
Optical Manipulation of Rashba Spin–Orbit Coupling at SrTiO<sub>3</sub>‑Based Oxide Interfaces
Spin–orbit
coupling (SOC) plays a crucial role for spintronics
applications. Here we present the first demonstration that the Rashba
SOC at the SrTiO<sub>3</sub>-based interfaces is highly tunable by
photoinduced charge doping, that is, optical gating. Such optical
manipulation is nonvolatile after the removal of the illumination
in contrast to conventional electrostatic gating and also erasable
via a warming–cooling cycle. Moreover, the SOC evolutions tuned
by illuminations with different wavelengths at various gate voltages
coincide with each other in different doping regions and collectively
form an upward-downward trend curve: In response to the increase of
conductivity, the SOC strength first increases and then decreases,
which can be attributed to the orbital hybridization of Ti 3<i>d</i> subbands. More strikingly, the optical manipulation is
effective enough to tune the interferences of Bloch wave functions
from constructive to destructive and therefore to realize a transition
from weak localization to weak antilocalization. The present findings
pave a way toward the exploration of photoinduced nontrivial quantum
states and the design of optically controlled spintronic devices