Phys.org August 27, 2024 Due to their bosonic nature, excitons are expected to condense and exhibit superfluidity at sufficiently low temperatures. In interacting Chern insulators, excitons may inherit the nontrivial topology and quantum geometry from the underlying electron wavefunctions. A team of researchers in the US (University of Oklahoma, City University of New York, Harvard University) theoretically investigated the excitonic bound states and superfluidity in flat-band insulators pumped with light. They found that the exciton wavefunctions exhibited vortex structures in momentum space, with the total vorticity being equal to the difference of Chern numbers between the conduction and valence bands. […]
Category Archives: Exitons
Physicists shine light on solid way to extend excitons’ life
Phys.org June 20, 2022 A team of researchers in the US (UT Austin, Auburn University) performed an extensive study of transient optical absorption of both W- and Mo-based single-crystalline monolayer TMDs grown by a recently developed laser-assisted evaporation method. All spectral features of the monolayers as grown on fused silica substrates exhibited appreciable redshifts relating to the existence of strain due to growth conditions. These systems exhibited a dramatic slowing down of exciton dynamics with an increase in carrier densities, which strongly contrasted with the monolayers in their freestanding form as well as in comparison with more traditionally grown TMDs. […]
Physicists manipulate magnetism with light
Nanowerk January 28, 2022 The non-equilibrium driving of dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. An international team of researchers (USA – MIT, South Korea) achieved this in the van der Waals correlated insulator NiPS3 by photoexciting its newly discovered spin–orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, they observed the coexistence of itinerant carriers produced by exciton dissociation and a long-wavelength antiferromagnetic magnon that coherently processes in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, […]
Exotic spiraling electrons discovered by physicists
Phys.org February 18, 2019 Excitons form when intense light shines on solids, kicking negatively charged electrons out of their spots and leaving behind positively charged holes. A team of researchers in the US (Rutgers University, University of Florida, North Carolina State University) has discovered chiral surface exciton on the surface of bismuth selenide. Chiral exiton consists of particles and anti-particles bound together and swirling around each other on the surface of solids. The electrons and holes resemble rapidly spinning tops. The electrons eventually “spiral” towards the holes, annihilating each other in less than a trillionth of a second while emitting […]
Scientists use excitons to take electronics into the future
Nanowerk July 25, 2018 An international team of researchers (Switzerland, Japan) made excitonic devices made of MoS2–WSe2 van der Waals heterostructures encapsulated in hexagonal boron nitride that demonstrate electrically controlled transistor actions at room temperature. The long-lived nature of the interlayer excitons in the devices results in them diffusing over five micrometres. Within the device, they have demonstrated the ability to manipulate exciton dynamics by creating electrically reconfigurable confining and repulsive potentials for the exciton flux. The research shows that it will be possible to integrate optical transmission and electronic data-processing systems into the same device, which will reduce the […]