ANDREEV REFLECTION AND SUBGAP TRANSPORT DUE TO ELECTRON-MAGNON INTERACTIONS IN FERROMAGNET-SUPERCONDUCTOR JUNCTIONS

2003 ◽  
Vol 17 (28) ◽  
pp. 5001-5005 ◽  
Author(s):  
G. TKACHOV ◽  
E. MCCANN ◽  
V. I. FAL'KO
Keyword(s):  
Low Temperature ◽  
Density Of States ◽  
Andreev Reflection ◽  
Cooper Pair ◽  
Local Density ◽  
Green Functions ◽  
Local Density Of States ◽  
Hamiltonian Method ◽  
New Process ◽  
Additional Channel

We show that electron-magnon interactions at a ferromagnetic metal-superconductor interface lead to a new process of magnon-assisted Andreev reflection, which consists of the simultaneous injection of a Cooper pair from the superconductor and the emission of a magnon inside the ferromagnet. At low temperature this process represents an additional channel for subgap transport across an FS interface, which lifts restrictions on the current I resulting from the necessity to match spin-polarised current in the ferromagnet with spin-less current in the superconductor. We calculate I using the tunnelling Hamiltonian method and the nonequilibrium (Keldysh) Green functions technique. It is shown that the inelastic magnon-assisted Andreev process would manifest itself as a nonlinear addition to the I(V) characteristics which is asymmetric with respect to the sign of the bias voltage and is related to the local density of states of magnons at the interface.

Measurement of Local Density of States by Scanning Tunneling Spectroscopy at Low Temperature

1987 ◽  
Vol 26 (S3-1) ◽  
pp. 627 ◽  
Author(s):  
Hiroshi Bando ◽  
Hiroshi Tokumoto ◽  
Wataru Mizutani ◽  
Kazuhiro Endo ◽  
Shigeru Wakiyama ◽  
...  
Keyword(s):  
Low Temperature ◽  
Density Of States ◽  
Local Density ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Local Density Of States

scholarly journals Supersymmetric Cluster Expansions and Applications to Random Schrödinger Operators

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Luca Fresta
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Schrödinger Operators ◽  
Random Schrödinger Operators ◽  
Schrodinger Operators ◽  
Local Density Of States ◽  
Weak Disorder ◽  
Cluster Expansions ◽  
Strong Disorder ◽  
Lifshitz Tail

AbstractWe study discrete random Schrödinger operators via the supersymmetric formalism. We develop a cluster expansion that converges at both strong and weak disorder. We prove the exponential decay of the disorder-averaged Green’s function and the smoothness of the local density of states either at weak disorder and at energies in proximity of the unperturbed spectrum or at strong disorder and at any energy. As an application, we establish Lifshitz-tail-type estimates for the local density of states and thus localization at weak disorder.

scholarly journals Near-Field Excitation of Bound States in the Continuum in All-Dielectric Metasurfaces through a Coupled Electric/Magnetic Dipole Model

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 998
Author(s):  
Diego R. Abujetas ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Dipole ◽  
Density Of States ◽  
Bound States ◽  
Local Density ◽  
Near Field ◽  
Field Pattern ◽  
Local Density Of States ◽  
Optical Modes ◽  
Source Excitation ◽  
The Continuum

Resonant optical modes arising in all-dielectric metasurfaces have attracted much attention in recent years, especially when so-called bound states in the continuum (BICs) with diverging lifetimes are supported. With the aim of studying theoretically the emergence of BICs, we extend a coupled electric and magnetic dipole analytical formulation to deal with the proper metasurface Green function for the infinite lattice. Thereby, we show how to excite metasurface BICs, being able to address their near-field pattern through point-source excitation and their local density of states. We apply this formulation to fully characterize symmetry-protected BICs arising in all-dielectric metasurfaces made of Si nanospheres, revealing their near-field pattern and local density of states, and, thus, the mechanisms precluding their radiation into the continuum. This formulation provides, in turn, an insightful and fast tool to characterize BICs (and any other leaky/guided mode) near fields in all-dielectric (and also plasmonic) metasurfaces, which might be especially useful for the design of planar nanophotonic devices based on such resonant modes.

MODIFICATION OF CASIMIR FORCES DUE TO BAND GAPS IN PERIODIC STRUCTURES

2002 ◽  
Vol 17 (06n07) ◽  
pp. 798-803 ◽  
Author(s):  
C. VILLARREAL ◽  
R. ESQUIVEL-SIRVENT ◽  
G. H. COCOLETZI
Keyword(s):  
Density Of States ◽  
Casimir Force ◽  
Periodic Structures ◽  
Local Density ◽  
Band Gaps ◽  
Basic Unit ◽  
Local Density Of States ◽  
Casimir Forces ◽  
Unit Cells ◽  
The Difference

The Casimir force between inhomogeneous slabs that exhibit a band-like structure is calculated. The slabs are made of basic unit cells each made of two layers of different materials. As the number of unit cells increases the Casimir force between the slabs changes, since the reflectivity develops a band-like structure characterized by frequency regions of high reflectivity. This is also evident in the difference of the local density of states between free and boundary distorted vacuum, that becomes maximum at frequencies corresponding to the band gaps. The calculations are restricted to vacuum modes with wave vectors perpendicular to the slabs.

scholarly journals Checkerboard local density of states in striped domains pinned by vortices

2003 ◽  
Vol 67 (13) ◽  
Author(s):  
Brian Møller Andersen ◽  
Per Hedegård ◽  
Henrik Bruus
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Local Density Of States

scholarly journals Inferring effective interactions from the local density of states: Application to STM data fromBi2Sr2CaCu2O8+δ

2006 ◽  
Vol 74 (17) ◽  
Author(s):  
R. Jamei ◽  
J. Robertson ◽  
E-A. Kim ◽  
A. Fang ◽  
A. Kapitulnik ◽  
...  
Keyword(s):  
Density Of States ◽  
Local Density ◽  
Local Density Of States ◽  
Effective Interactions
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