scholarly journals Long-range focusing of magnetic bound states in superconducting lanthanum

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Howon Kim ◽  
Levente Rózsa ◽  
Dominik Schreyer ◽  
Eszter Simon ◽  
Roland Wiesendanger
Keyword(s):  
Long Range ◽  
Bound States ◽  
Theoretical Calculations ◽  
Surface States ◽  
Magnetic Interactions ◽  
Magnetic Impurities ◽  
Natural Choice ◽  
Temperature Scanning ◽  
Quantum Mechanical Systems ◽  
Low Dimensional

Abstract Quantum mechanical systems with long-range interactions between quasiparticles provide a promising platform for coherent quantum information technology. Superconductors are a natural choice for solid-state based quantum devices, while magnetic impurities inside superconductors give rise to quasiparticle excitations of broken Cooper pairs that provide characteristic information about the host superconductor. Here, we reveal that magnetic impurities embedded below a superconducting La(0001) surface interact via quasiparticles extending to very large distances, up to several tens of nanometers. Using low-temperature scanning probe techniques, we observe the corresponding anisotropic and giant oscillations in the LDOS. Theoretical calculations indicate that the quasi-two-dimensional surface states with their strongly anisotropic Fermi surface play a crucial role for the focusing and long-range extension of the magnetic bound states. The quasiparticle focusing mechanism should facilitate the design of versatile magnetic structures with tunable and directed magnetic interactions over large distances, thereby paving the way toward the design of low-dimensional magnet–superconductor hybrid systems exhibiting topologically non-trivial quantum states as possible elements of quantum computation schemes based on Majorana quasiparticles.

scholarly journals Spin-orbit coupling induced splitting of Yu-Shiba-Rusinov states in antiferromagnetic dimers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Philip Beck ◽  
Lucas Schneider ◽  
Levente Rózsa ◽  
Krisztián Palotás ◽  
András Lászlóffy ◽  
...  
Keyword(s):  
Bound States ◽  
Theoretical Calculations ◽  
Building Blocks ◽  
Orbit Coupling ◽  
Topological Classification ◽  
Cooper Pairs ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Low Dimensional

AbstractMagnetic atoms coupled to the Cooper pairs of a superconductor induce Yu-Shiba-Rusinov states (in short Shiba states). In the presence of sufficiently strong spin-orbit coupling, the bands formed by hybridization of the Shiba states in ensembles of such atoms can support low-dimensional topological superconductivity with Majorana bound states localized on the ensembles’ edges. Yet, the role of spin-orbit coupling for the hybridization of Shiba states in dimers of magnetic atoms, the building blocks for such systems, is largely unexplored. Here, we reveal the evolution of hybridized multi-orbital Shiba states from a single Mn adatom to artificially constructed ferromagnetically and antiferromagnetically coupled Mn dimers placed on a Nb(110) surface. Upon dimer formation, the atomic Shiba orbitals split for both types of magnetic alignment. Our theoretical calculations attribute the unexpected splitting in antiferromagnetic dimers to spin-orbit coupling and broken inversion symmetry at the surface. Our observations point out the relevance of previously unconsidered factors on the formation of Shiba bands and their topological classification.

High resolution spectrum of NO2 loosely bound states: densities of states and long range forces

2001 ◽  
Vol 3 (12) ◽  
pp. 2268-2274 ◽  
Author(s):  
Sylvain Heilliette ◽  
Antoine Delon ◽  
Patrick Dupre´ ◽  
Re´my Jost
Keyword(s):  
High Resolution ◽  
Long Range ◽  
Bound States ◽  
High Resolution Spectrum ◽  
Densities Of States

Comparative Optical Studies of Chemically Synthesized Silicon Nanocrystals

1996 ◽  
Vol 452 ◽  
Author(s):  
Gildardo R. Delgado ◽  
Howard W.H. Lee ◽  
Susan M. Kauzlarich ◽  
Richard A. Bley
Keyword(s):  
Porous Silicon ◽  
Silicon Nanocrystals ◽  
Surface Passivation ◽  
Theoretical Calculations ◽  
Dominant Role ◽  
Blue Emission ◽  
Surface States ◽  
Si Nanocrystals ◽  
Optical And Electronic Properties ◽  
Passivation Layers

AbstractWe studied the optical and electronic properties of silicon nanocrystals derived from two distinct fabrication procedures. One technique uses a controlled chemical reaction. In the other case, silicon nanocrystals are produced by ultrasonic fracturing of porous silicon layers. We report on the photoluminescence, photoluminescence excitation, and absorption spectroscopy of various size distributions derived from these techniques. We compare the different optical properties of silicon nanocrystals made this way and contrast them with that observed in porous silicon. Our results emphasize the dominant role of surface states in these systems as manifested by the different surface passivation layers present in these different fabrication techniques. Experimental absorption measurements are compared to theoretical calculations with good agreement. Our results provide compelling evidence for quantum confinement in both types of Si nanocrystals. Our results also indicate that the blue emission from very small Si nanocrystals corresponds to the bandedge emission, while the red emission arises from traps.

Permanent Dipole of Metal−Benzene Molecules: Evidence for Long-Range Weakly Bound States?

2003 ◽  
Vol 107 (51) ◽  
pp. 11347-11353 ◽  
Author(s):  
F. Rabilloud ◽  
D. Rayane ◽  
A. R. Allouche ◽  
R. Antoine ◽  
M. Aubert-Frécon ◽  
...  
Keyword(s):  
Long Range ◽  
Bound States ◽  
Weakly Bound

scholarly journals Magnetic and defect probes of the SmB6 surface state

2018 ◽  
Vol 4 (11) ◽  
pp. eaau4886 ◽  
Author(s):  
Lin Jiao ◽  
Sahana Rößler ◽  
Deepa Kasinathan ◽  
Priscila F. S. Rosa ◽  
Chunyu Guo ◽  
...  
Keyword(s):  
Surface States ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Magnetic Impurities ◽  
Fundamental Physics ◽  
Length Scales ◽  
Kondo Insulator ◽  
Theoretical Predictions ◽  
The Impact

The impact of nonmagnetic and magnetic impurities on topological insulators is a central focus concerning their fundamental physics and possible spintronics and quantum computing applications. Combining scanning tunneling spectroscopy with transport measurements, we investigate, both locally and globally, the effect of nonmagnetic and magnetic substituents in SmB6, a predicted topological Kondo insulator. Around the so-introduced substitutents and in accord with theoretical predictions, the surface states are locally suppressed with different length scales depending on the substituent’s magnetic properties. For sufficiently high substituent concentrations, these states are globally destroyed. Similarly, using a magnetic tip in tunneling spectroscopy also resulted in largely suppressed surface states. Hence, a destruction of the surface states is always observed close to atoms with substantial magnetic moment. This points to the topological nature of the surface states in SmB6 and illustrates how magnetic impurities destroy the surface states from microscopic to macroscopic length scales.

scholarly journals Configurational Statistics

1978 ◽  
Vol 21 (85) ◽  
pp. 73-83 ◽  
Author(s):  
J. F. Nagle
Keyword(s):  
Dielectric Constant ◽  
Long Range ◽  
Short Range ◽  
Theoretical Calculations ◽  
Correlation Factor ◽  
Residual Entropy ◽  
Dipolar Interactions ◽  
Computational Tool ◽  
Kirkwood Correlation Factor ◽  
Polarization Factor

Abstract Theories of the dielectric constant in ice differ in three fundamentally different ways that are often confused with each other. First, there is the choice of interactions to include in the model, notably whether to try to include long-range dipolar interactions as in the Kirkwood theory or to include only the short-range ice-rule interactions. Second, there is the choice of the kind of statistical quantity calculated, e.g. the Kirkwood correlation factor g or the polarization factor G, which Stillinger and Cotter showed to be different. Finally, there is the choice of the kind of computational tool used, and in original papers this choice often obscures the first two differences. With these distinctions in mind a review is given of current theoretical calculations of the dielectric constant and the residual entropy and how the different theories relate to each other and to experiments.

scholarly journals Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

2011 ◽  
Vol 2 ◽  
pp. 552-560 ◽  
Author(s):  
Miriam Jaafar ◽  
Oscar Iglesias-Freire ◽  
Luis Serrano-Ramón ◽  
Manuel Ricardo Ibarra ◽  
Jose Maria de Teresa ◽  
...  
Keyword(s):  
Long Range ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Superparamagnetic Nanoparticles ◽  
Kelvin Probe Force Microscopy ◽  
Magnetic Interactions ◽  
Kelvin Probe ◽  
Force Microscopy

The most outstanding feature of scanning force microscopy (SFM) is its capability to detect various different short and long range interactions. In particular, magnetic force microscopy (MFM) is used to characterize the domain configuration in ferromagnetic materials such as thin films grown by physical techniques or ferromagnetic nanostructures. It is a usual procedure to separate the topography and the magnetic signal by scanning at a lift distance of 25–50 nm such that the long range tip–sample interactions dominate. Nowadays, MFM is becoming a valuable technique to detect weak magnetic fields arising from low dimensional complex systems such as organic nanomagnets, superparamagnetic nanoparticles, carbon-based materials, etc. In all these cases, the magnetic nanocomponents and the substrate supporting them present quite different electronic behavior, i.e., they exhibit large surface potential differences causing heterogeneous electrostatic interaction between the tip and the sample that could be interpreted as a magnetic interaction. To distinguish clearly the origin of the tip–sample forces we propose to use a combination of Kelvin probe force microscopy (KPFM) and MFM. The KPFM technique allows us to compensate in real time the electrostatic forces between the tip and the sample by minimizing the electrostatic contribution to the frequency shift signal. This is a great challenge in samples with low magnetic moment. In this work we studied an array of Co nanostructures that exhibit high electrostatic interaction with the MFM tip. Thanks to the use of the KPFM/MFM system we were able to separate the electric and magnetic interactions between the tip and the sample.

scholarly journals Qubit-photon bound states in topological waveguides with long-range hoppings

2021 ◽  
Vol 104 (5) ◽  
Author(s):  
C. Vega ◽  
M. Bello ◽  
D. Porras ◽  
A. González-Tudela
Keyword(s):  
Long Range ◽  
Bound States
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