scholarly journals Role of real-space micromotion for bosonic and fermionic Floquet fractional Chern insulators

2015 ◽  
Vol 91 (24) ◽  
Author(s):  
Egidijus Anisimovas ◽  
Giedrius Žlabys ◽  
Brandon M. Anderson ◽  
Gediminas Juzeliūnas ◽  
André Eckardt
Keyword(s):  
Real Space ◽  
Chern Insulators

scholarly journals Real-space observation of ferroelectrically induced magnetic spin crystal in SrRuO3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. D. Seddon ◽  
D. E. Dogaru ◽  
S. J. R. Holt ◽  
D. Rusu ◽  
J. J. P. Peters ◽  
...  
Keyword(s):  
Hall Effect ◽  
Density Functional ◽  
Hysteresis Loops ◽  
Real Space ◽  
Zero Field ◽  
Force Microscopy ◽  
Switching Regime ◽  
Conflicting Evidence ◽  
Magnetic Spin

AbstractUnusual features in the Hall Resistivity of thin film systems are frequently associated with whirling spin textures such as Skyrmions. A host of recent investigations of Hall Hysteresis loops in SrRuO3 heterostructures have provided conflicting evidence for different causes for such features. We have constructed an SrRuO3-PbTiO3 (Ferromagnetic – Ferroelectric) bilayer that exhibits features in the Hall Hysteresis previously attributed to a Topological Hall Effect, and Skyrmions. Here we show field dependent Magnetic Force Microscopy measurements throughout the key fields where the ‘THE’ presents, revealing the emergence to two periodic, chiral spin textures. The zero-field cycloidal phase, which then transforms into a ‘double-q’ incommensurate spin crystal appears over the appearance of the ‘Topological-like’ Hall effect region, and develop into a ferromagnetic switching regime as the sample reaches saturation, and the ‘Topological-like’ response diminishes. Scanning Tunnelling Electron Microscopy and Density Functional Theory is used to observe and analyse surface inversion symmetry breaking and confirm the role of an interfacial Dzyaloshinskii–Moriya interaction at the heart of the system.

scholarly journals Local Spin and Open Quantum Systems: Clarifying Misconceptions, Unifying Approaches

2020 ◽  
Author(s):  
Angel Martín Pendás ◽  
Evelio Francisco
Keyword(s):  
Quantum Control ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Real Space ◽  
Quantum Systems ◽  
Spin Coupling ◽  
Molecular Systems ◽  
Open Quantum ◽  
Local Spin

<p>We now show that Clark and Davidson local spins operators are perfectly defined subsystem operators if a fragment is taken as an <i>open quantum system</i> (OQS). Open systems have become essential in quantum control and quantum computation, but have not received much attention in Chemistry. We have already shown (<i>J. Chem. Theory Comput</i>. <b>2018</b>, <i>15</i>, 1079) how real space OQSs can be defined in molecular systems and how they offer new insights relating quantum mechanical entaglement and chemical bonding. The OQS account of local spin that we offer yields a rigorous, yet easily accessible way to rationalize local spin values. A fragment is found in a mixed state direct sum of sectors characterized by different number of electrons that occur with different probabilities. The local spin is then a weighted sum of otherwise standard <i>S</i>(<i>S</i>+1) values. With OQS glasses, it is obvious that atomic or fragment spins should not vanish. Our approach thus casts doubts on any procedure used to annihilate them, like those used by Mayer and coworkers. OQS local spins allow for a fruitful use of models. One can propose easily sector probabilities for localized, covalent, ionic, zwitterionic, etc. situations, and examine their ideal local spins. We have mapped all 2c-2e cases, and shown how to do that in general multielectron cases. The role of electron correlation is also studied by tuning the Hubbard U/t parameter for H chains. Correlation induced localization changes the spin-coupling patterns even qualitatively, and show how the limiting antiferromagnet arises.</p>

scholarly journals Phase Separation in the Two-Dimensional Systems of Strongly Correlated Electrons: The Role of Spin Singlet Pairs on Hole Pairing Contribution to Hole-Rich Phase

2005 ◽  
Vol 277-279 ◽  
pp. 1011-1016
Author(s):  
Sung Sik Lee ◽  
Sul Ah Ahn ◽  
Sung Ho Suck Salk
Keyword(s):  
Phase Separation ◽  
Strongly Correlated Electrons ◽  
Real Space ◽  
Correlated Electrons ◽  
Hole Density ◽  
Strongly Correlated ◽  
Two Dimensional ◽  
Rich Phase ◽  
Spin Singlet

By paying attention to the hole-doped two-dimensional systems of antiferromagnetically (strongly) correlated electrons, we discuss the cause of hole-rich phase formation in association with phase separation. We show that the phase diagram obtained from Maxwell's construction in the plane of temperature vs. hole density is consistent with one derived from the evaluation of hole-rich and electron-rich phases in real space. We observe that the formation of a hole-rich phase is attributed to the aggregation of hole pairs induced by spin singlet pairs present in the pseudogap phase, and that the direct involvement of correlations between hole pairs is not essential for phase separation.

scholarly journals Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

2015 ◽  
Vol 71 (6) ◽  
pp. 641-647 ◽  
Author(s):  
Rachel E. Fletcher ◽  
Stephen A. Wells ◽  
Ka Ming Leung ◽  
Peter P. Edwards ◽  
Asel Sartbaeva
Keyword(s):  
Real Space ◽  
Ionic Conductors ◽  
Static Properties ◽  
Zeolite Framework ◽  
Framework Materials ◽  
Collective Motions ◽  
The Cost ◽  
Insight Into ◽  
Shed Light

Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves – as in the case of silicates, where the geometry of the SiO4 tetrahedral group is much more strongly constrained than the Si—O—Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the `rigid unit mode' (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the `flexibility window' phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework.

Carthage—Rome—Milan

2018 ◽  
Author(s):  
Therese Fuhrer
Keyword(s):  
Real Space ◽  
History Of Philosophy ◽  
Early Years ◽  
Urban Spaces ◽  
Late Antique ◽  
Henri Lefebvre ◽  
History Of ◽  
The Absolute ◽  
Abstract Spaces

In the autobiographical narrative of Confessions 3 to 9, Augustine stages his early years in the urban spaces of Carthage, Rome, and Milan, which are among the most important cities of the late antique world. Each of these cities is assigned the role of a transit point on the way to moral and theological purification, associated with events and experiences that are subsequently assigned a particular significance which is transferred onto the place. Augustine’s Bildungsroman is thus also a kind of travel novel in a landscape defined by emotions and intellectual achievements; that is, in a psychogeography that leads ever further into the ‘inner person’, and reveals what is often interpreted in the history of philosophy as the discovery of subjectivity and interiority. Augustine’s narrative thus produces a series of imaginary or—according to Henri Lefebvre—‘abstract spaces’ which overlay, but do not erase, the ‘absolute’ or ‘real space’.

Defect and Equivalence of Unitary Matrices. The Fourier Case. Part II

2019 ◽  
Vol 26 (01) ◽  
pp. 1950003 ◽  
Author(s):  
Wojciech Tadej
Keyword(s):  
Prime Number ◽  
Unitary Operator ◽  
Real Space ◽  
Finite Abelian Groups ◽  
Unitary Matrices ◽  
First Order ◽  
Case Part ◽  
Fourier Matrix

Consider the real space 𝔻U of directions one can move in from a unitary N × N matrix U without disturbing its unitarity and the moduli of its entries in the first order. dimℝ (𝔻U) is called the defect of U and denoted D(U). We give an account of Alexander Karabegov’s theory where 𝔻U is parametrized by the imaginary subspace of the eigenspace, associated with λ = 1, of a certain unitary operator ℐU on 𝕄N, and where D(U) is the multiplicity of 1 in the spectrum of ℐU. This characterisation allows us to establish the dependence of D(U(1) ⊗ … ⊗ U(r)) on D(U(k))’s, to derive formulas expressing D(F) for a Fourier matrix F of the size being a power of a prime number, as well as to show the multiplicativity of D(F) with respect to Kronecker factors of F if their sizes are pairwise relatively prime. Also partly due to the role of symmetries of U in the determination of the eigenspaces of ℐU we study the ‘permute and enphase’ symmetries and equivalence of Fourier matrices, associated with arbitrary finite abelian groups. This work is published as two papers — the first part [1] and the current second one.

scholarly journals Simulation of relativistic electron generation in under-dense laser plasma experiments

1997 ◽  
Vol 15 (1) ◽  
pp. 197-211
Author(s):  
G. Manfredi ◽  
R. Bingham ◽  
R.O. Dendy
Keyword(s):  
Dense Plasma ◽  
Real Space ◽  
Electron Velocity ◽  
Relativistic Electrons ◽  
Direct Solution ◽  
Electron Velocity Distribution ◽  
Electron Generation ◽  
Back Ground ◽  
The Impact

The generation of relativistic electrons by nonlinear coupling of a laser beam to an under-dense plasma is simulated. An Eulerian Vlasov code is used, which enables direct solution of the fully nonlinear Vlasov-Maxwell system in real space. The impact of stimulated Raman and Compton scattering on the electron velocity distribution is investigated. Simulations show that electrons can be accelerated to energies of several MeV. The role of induced scattering processes is analyzed in detail, using electromagnetic field spectra and electron phase-space information as diagnostics. The effects of density gradients in the back-ground plasma are also quantified.

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