Plexcitons are

polariton In physics, polaritons are bosonic quasiparticles resulting from strong coupling of electromagnetic waves (photon) with an electric or magnetic dipole-carrying excitation (state) of solid or liquid matter (such as a phonon, plasmon, or an exc ...

ic modes that result from coherently coupled

plasmon In physics, a plasmon is a quantum of plasma oscillation. Just as light (an optical oscillation) consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quant ...

s and

exciton An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb's law, Coulomb force resulting from their opposite charges. It is an electrically neutral quasiparticle regarded as ...

s. Plexcitons aid direct energy flows in exciton energy transfer (EET). Plexcitons travel for 20 μm, similar to the width of a human hair.

History

Plasmons are a quantity of collective electron oscillations. Excitons are excited electrons bound to the hole produced by their excitation. Molecular crystal excitons were combined with the collective excitations within metals to create plexcitons. This allowed EET to reach distances of around 20,000 nanometers, an enormous increase over the some 10 nanometers possible previously. However, the transfer direction was uncontrolled.

Topological insulators A topological insulator is a material whose interior behaves as an electrical insulator while its surface behaves as an electrical conductor, meaning that electrons can only move along the surface of the material. A topological insulator is an ...

(TI) act as insulators below their surface, but have conductive surfaces, constraining

electrons The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

to move only along that surface. Even materials with moderately flawed surfaces do not impede current flow. Topological plexcitons make use of the properties of TIs to achieve similar control over the direction of current flow. Plexcitons were found to emerge from an organic molecular layer (excitons) and a metallic film (plasmons).

Dirac cone In physics, Dirac cones are features that occur in some electronic band structures that describe unusual electron transport properties of materials like graphene and topological insulators. In these materials, at energies near the Fermi leve ...

s appeared in the plexcitons' two-dimensional band-structure. An external magnetic field created a gap between the cones when the system was interfaced to a magneto-optical layer. The resulting energy gap became populated with topologically protected one-way modes, which traveled only at the system interface.

Potential applications

Plexcitons potentially offer an appealing platform for exploring exotic matter phases and for controlling nanoscale energy flows.

References

External links

* {{Cite journal, last1=Ozel, first1=Tuncay, last2=Hernandez-Martinez, first2=Pedro Ludwig, last3=Mutlugun, first3=Evren, last4=Akin, first4=Onur, last5=Nizamoglu, first5=Sedat, last6=Ozel, first6=Ilkem Ozge, last7=Zhang, first7=Qing, last8=Xiong, first8=Qihua, last9=Demir, first9=Hilmi Volkan, date=2013-07-10, title=Observation of Selective Plasmon-Exciton Coupling in Nonradiative Energy Transfer: Donor-Selective versus Acceptor-Selective Plexcitons, journal=Nano Letters, volume=13, issue=7, pages=3065–3072, doi=10.1021/nl4009106, pmid=23755992, issn=1530-6984, bibcode=2013NanoL..13.3065O, hdl=11693/12141, hdl-access=free Quasiparticles Plasmonics