Search results for "Local density of states"
showing 6 items of 16 documents
Direct interpretation of near-field optical images.
2001
The interpretation of the detection process in near-field optical microscopy is reviewed on the basis of a discussion about the possibility of establishing direct comparisons between experimental images and the solutions of Maxwell equations or the electromagnetic local density of states. On the basis of simple physical arguments, it is expected that the solutions of Maxwell equations should agree with images obtained by collecting mode near-field microscopes, while the electromagnetic local density of states should be considered to provide a practical interpretation of illumination mode near-field microscopes. We review collecting mode near-field microscope images where the conditions to o…
Generalized bloch equations for optical interactions in confined geometries
2005
By combining the field-susceptibility technique with the optical Bloch equations, a general formalism is developed for the investigation of molecular photophysical phenomena triggered by nanometer scale optical fields in the presence of complex environments. This formalism illustrate the influence of the illumination regime on the fluorescence signal emitted by a single molecule in a complex environment. In the saturated case, this signal is proportional to the optical local density of states, while it is proportional to the near-field intensity in the non-saturated case. (C) 2005 Elsevier B.V. All rights reserved.
Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field.
2016
One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudo-magnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudo-magnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudo-magnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene's pseudospin due to a strain induced pseudo-magnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining grap…
Odd triplet superconductivity induced by the moving condensate
2020
It has been commonly accepted that magnetic field suppresses superconductivity by inducing the ordered motion of Cooper pairs. We demonstrate that magnetic field can instead provide a generation of superconducting correlations by inducing the motion of superconducting condensate. This effect arises in superconductor/ferromagnet heterostructures in the presence of Rashba spin-orbital coupling. We predict the odd-frequency spin-triplet superconducting correlations called the Berezinskii order to be switched on at large distances from the superconductor/ferromagnet interface by the application of a magnetic field. This is shown to result in the unusual behaviour of Josephson effect and local d…
Theoretical principles of near-field optical microscopies and spectroscopies
2000
International audience; This paper deals with the principles of detection of optical signals near a surface in a manner permitting the mapping of the distribution of the fields close to various kinds of illuminated samples. We begin with a discussion of the main physical properties of the optical fields near a surface in the absence of any probe tip. This mainly concerns phenomena involving evanescent waves for which the local decay lengths are governed not only by the sizes but also by the intrinsic properties of the surface structures. The interpretation of the detection process is reviewed on the basis of a discussion about the possibility of establishing direct comparisons between exper…
Flat-band superconductivity in strained Dirac materials
2016
We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly increased critical temperature compared to the case without the strain, inhomogenous order parameter with two-peak shaped local density of states and yet a large and almost uniform and isotropic supercurrent. This model could be realized in strained graphene or ultracold atom systems and could be responsible for unusually strong superconductivity observed in some graphite interfaces and certain IV-VI semiconductor heterostructures.