32,486 research outputs found
Phosphorene nanoribbons
Edge-induced gap states in finite phosphorene layers are examined using
analytical models and density functional theory. The nature of such gap states
depends on the direction of the cut. Armchair nanoribbons are insulating,
whereas nanoribbons cut in the perpendicular direction (with zigzag and
cliff-type edges) are metallic, unless they undergo a reconstruction or
distortion with cell doubling, which opens a gap. All stable nanoribbons with
unsaturated edges have gap states that can be removed by hydrogen passivation.
Armchair nanoribbon edge states decay exponentially with the distance to the
edge and can be described by a nearly-free electron model
2D materials and van der Waals heterostructures
The physics of two-dimensional (2D) materials and heterostructures based on
such crystals has been developing extremely fast. With new 2D materials, truly
2D physics has started to appear (e.g. absence of long-range order, 2D
excitons, commensurate-incommensurate transition, etc). Novel heterostructure
devices are also starting to appear - tunneling transistors, resonant tunneling
diodes, light emitting diodes, etc. Composed from individual 2D crystals, such
devices utilize the properties of those crystals to create functionalities that
are not accessible to us in other heterostructures. We review the properties of
novel 2D crystals and how their properties are used in new heterostructure
devices
Charge orders, magnetism and pairings in the cuprate superconductors
We review the recent developments in the field of cuprate superconductors
with the special focus on the recently observed charge order in the underdoped
compounds. We introduce new theoretical developments following the study of the
antiferromagnetic (AF) quantum critical point (QCP) in two dimensions, in which
preemptive orders in the charge and superconducting (SC) sectors emerged, that
are in turn related by an SU(2) symmetry. We consider the implications of this
proliferation of orders in the underdoped region, and provide a study of the
type of fluctuations which characterize the SU(2) symmetry. We identify an
intermediate energy scale where the SU(2) pairing fluctuations are dominant and
argue that they are unstable towards the formation of a Resonant Peierls
Excitonic (RPE) state at the pseudogap (PG) temperature . We discuss the
implications of this scenario for a few key experiments.Comment: 16 pages, 17 figure
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