Since the formulation of geometric phase by Berry, its relevance has been demonstrated in a large variety physical systems. However, most fundamental spin-1/2 system, electron spin, not observed directly and controlled independently from dynamical phases. Here we report experimental evidence on manipulation an spin through purely effect InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying in-plane magnetic field, shift Aharonov–Casher interference pattern towards small...

The main theme of this review is the many-body physics vortices in quantum droplets bosons or fermions limit small particle numbers. Systems interest include cold atoms traps as well electrons confined dots. When set to rotate, these principle different systems show remarkable analogies. topics reviewed structure finite rotating state, universality vortex formation and localization both bosonic fermionic systems, emergence particle-vortex composites Hall regime. An overview computational...

Spin-transistor designs relying on spin-orbit interaction suffer from low signal levels resulting spin-injection efficiency and fast spin decay. Here, we present an alternative approach in which information is protected by propagating this adiabatically. We demonstrate the validity of our a cadmium manganese telluride diluted magnetic semiconductor quantum well structure efficient transport observed over device distances 50 micrometers. The turned "off" introducing diabatic Landau-Zener...

Abstract A characteristic feature of the state‐of‐the‐art real‐space methods in electronic structure calculations is diversity techniques used discretization relevant partial differential equations. In this context, main approaches include finite‐difference methods, various types finite‐elements and wavelets. This paper reports on results several code development projects that approach problems related to using these three different methods. We review ideas behind give examples their...

We study the ground-state properties of rectangular quantum dots by using spin-density-functional theory and Monte Carlo methods. The dot geometry is determined an infinite hard-wall potential to enable comparison manufactured, rectangular-shaped dots. show that electronic structure very sensitive shape dot, and, at realistic sizes, noninteracting picture determines general behavior. However, close degenerate points where Hund's rule applies, we find spin-density-wave-like solutions...

We study electronic structures of two-dimensional quantum dots in strong magnetic fields using mean-field density-functional theory and exact diagonalization. Our numerically accurate solutions show a reconstruction the uniform-density electron droplet when field flux quanta enter one by dot stronger fields. These correspond to repelling vortices forming polygonal clusters inside dot. find similar treatment problem constructing conditional operator for analysis. discuss important differences...

Abstract Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, which data encoded the domain transported using spin-polarised currents. However, development energy-efficient devices has been hampered by high current densities needed to initiate wall motion. We show here that a remarkable reduction critical density can be achieved for in-plane magnetised coupled CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic...

We study a model quantum dot system in an external magnetic field by using both spin-density-functional theory and current-spin density-functional theory. The theories are used with local approximations for the spin-density vorticity. reliabilities of different parametrizations exchange-correlation functionals tested comparing ensuing energetics Monte Carlo results. limit where vorticity dependence should be is discussed.

We show that topological transitions in electronic spin transport are feasible by a controlled manipulation of spin-guiding fields. The determined the topology fields texture through an effective Berry phase (related to winding parity modes around poles Bloch sphere), irrespective actual complexity nonadiabatic dynamics. This manifests as distinct dislocation interference pattern quantum conductance mesoscopic loops. phenomenon is robust against disorder, and can be experimentally exploited...

We develop the theory of magnetic domain wall motion in coupled double-layer systems where electrons can hop between layers giving rise to an antiferromagnetic coupling. demonstrate that force from interlayer coupling drives walls and effect extrinsic pinning is greatly reduced if are initially separated. The threshold current density for metastable spin-aligned configurations also much lower. conclude has a significant on mobility systems.

We present a detailed analysis of the broken-symmetry mean-field solutions using four-electron rectangular quantum dot as model system. Comparisons density-functional theory predictions with exact ones show that symmetry breaking results from single-configuration wave function used in approach. As general cure we scheme systematically incorporates several configurations into and restores symmetry. This is easily applicable to any

The coexistence of Rashba and Dresselhaus spin-orbit interactions (SOIs) in semiconductor quantum wells leads to an anisotropic effective field coupled carriers' spins. We demonstrate a gate-controlled anisotropy Aharonov-Casher (AC) spin interferometry experiments with InGaAs mesoscopic rings by using in-plane magnetic as probe. Supported perturbation-theory approach, we find that the SOI strength controls AC resistance via dynamic geometric phases establish ways manipulate them employing...

Two-dimensional semiconductor quantum dots are studied in the filling-factor range $2<\ensuremath{\nu}<3$. We find both theoretical and experimental evidence of a collective many-body phenomenon, where fraction trapped electrons form an incompressible spin droplet on highest occupied Landau level. The phenomenon occurs only when number dot is larger than $\ensuremath{\sim}30$. onset spin-droplet regime at $\ensuremath{\nu}=5∕2$. This proposes finite-geometry alternative to...

The emergence of half-integer filling-factor states, such as upsilon=5/2 and 7/2, is found in quantum dots by using numerical many-electron methods. These states have interesting similarities differences with their counterstates the two-dimensional electron gas. upsilon=1/2 are shown to high overlaps composite fermion states. lower overlap Pfaffian state indicates that electrons might not be paired dot geometry. predicted has a spin polarization, which may an impact on transport through devices.

We investigate the properties of many-electron systems in two-dimensional polygonal (triangle, square, pentagon, hexagon) potential wells by using density-functional theory. The development ground-state electronic structure as a function dot size is particular interest. First, we show that case two electrons, Wigner molecule formation agrees with previous exact diagonalization studies. Then present detail how spin symmetry breaks geometries theory applied. In several cases more than find...

We study the stability and structure of vortices emerging in two-dimensional quantum dots high magnetic fields. Our results obtained with exact diagonalization density-functional calculations show that vortex structures can be found various confining potentials. In nonsymmetric external potentials we find off-electron are localized giving rise to charge deficiency or holes electron density rotating currents around them. discuss role fluctuations formation is observable energetics system....

We study electronic structures of quasi-two-dimensional finite electron systems in high magnetic fields. The solutions the fractional quantum Hall regime are interpreted as liquids electrons and vortices. ground states classified according to number vortices inside droplet. theory predicts observable effects due vortex formation chemical potentials magnetization droplets. compare transitions those found transport experiments on a dot device find significant correspondence.

Spin accumulation is a crucial but imprecise concept in spintronics. In metal-based spintronics it characterized terms of semiclassical distribution functions. semiconductors with strong spin-orbit coupling the spin interpreted as superposition coherent eigenstates. Both views can be reconciled by taking into account electron-electron interaction: sufficiently self-consistent exchange field reduces to chemical potential difference between two bands even presence coupling. We demonstrate idea...

Electron spins in a two-dimensional electron gas can be manipulated by spin-orbit (SO) fields originating from either Rashba or Dresselhaus interactions with independent isotropic characteristics. Together, though, they produce anisotropic SO consequences on quantum transport through spin interference. Here we study the properties of modeled mesoscopic rings subject to and [001] couplings presence an additional in-plane Zeeman field acting as probe. By means one- simulations show that this...

We identify a series of topological transitions occurring in electronic spin transport when manipulating spin-guiding fields controlled by the geometric shape mesoscopic interferometers. They manifest as distinct inversions interference pattern quantum conductance experiments. establish that Rashba square loops develop weak-(anti)localization (absent other geometries ring loops) an in-plane Zeeman field is applied. These transitions, boosted nonadiabatic scattering, prove to have...

We calculate spin transport in two-dimensional waveguides the presence of spatially modulated Zeeman-split energy bands. show that a regime where evolution is predominantly adiabatic backscattering rate can be tuned via diabatic Landau-Zener transitions between spin-split bands [C. Betthausen et. al., Science 337, 324 (2012)]. This mechanism tolerant against spin-independent scattering processes. Completely spin-polarized systems full backscattering, and thus current switching. In partially...