7,643 research outputs found
Rashba Spin Interferometer
A spin interferometer utilizing the Rashba effect is proposed. The novel
design is composed of a one-dimensional (1D) straight wire and a 1D half-ring.
By calculating the norm of the superposed wave function, we derive analytical
expressions to describe the spin interference spectrum as a function of the
Rashba coupling strength. Presented spin interference results are identified to
include (i) the quantum-mechanical 4pi rotation effect, (ii) geometric effect,
and (iii) Shubnikov-de Haas-like beating effect.Comment: 3 pages, 3 figures, appears in the proceedings of the 10th Joint
MMM/Intermag Conferenc
Quantum World-line Monte Carlo Method with Non-binary Loops and Its Application
A quantum world-line Monte Carlo method for high-symmetrical quantum models
is proposed. Firstly, based on a representation of a partition function using
the Matsubara formula, the principle of quantum world-line Monte Carlo methods
is briefly outlined and a new algorithm using non-binary loops is given for
quantum models with high symmetry as SU(N). The algorithm is called non-binary
loop algorithm because of non-binary loop updatings. Secondary, one example of
our numerical studies using the non-binary loop updating is shown. It is the
problem of the ground state of two-dimensional SU(N) anti-ferromagnets. Our
numerical study confirms that the ground state in the small N <= 4 case is a
magnetic ordered Neel state, but the one in the large N >= 5 case has no
magnetic order, and it becomes a dimer state.Comment: 14 pages, 5 figures, Invited talk at the 18th Annual Workshop on
Recent Developments of Computer Simulation Studies in Condensed Matter
Physics, Athens, 7-11 March, 200
Broken spin-Hall accumulation symmetry by magnetic field and coexisted Rashba and Dresselhaus interactions
The spin-Hall effect in the two-dimensional electron gas (2DEG) generates
symmetric out-of-plane spin Sz accumulation about the current axis in the
absence of external magnetic field. Here we employ the real space
Landauer-Keldysh formalism [B. K. Nikolic et al., Phys. Rev. Lett. 95, 046601
(2005); Phys. Rev. B 73, 075303 (2006)] by considering a four-terminal setup to
investigate the circumstances in which this symmetry is broken. For the absence
of Dresselhaus interaction, starting from the applied out-of-plane B
corresponding to Zeeman splitting energy 0 - 0.5 times the Rashba hopping
energy tR, the breaking process is clearly seen. The influence of the Rashba
interaction on the magnetization of the 2DEG is studied herein. For coexisted
Rashba tR and Dresselhaus tD spin-orbit couplings in the absence of B,
interchanging tR and tD reverses the entire accumulation pattern.Comment: 3 pages, 2 figures, appears in the proceedings of 10th MMM/INTERMAG
conferenc
Discrete Frequency Selection of Frame-Based Stochastic Real-Time Tasks
Energy-efficient real-time task scheduling has been actively explored in the
past decade. Different from the past work, this paper considers schedulability
conditions for stochastic real-time tasks. A schedulability condition is first
presented for frame-based stochastic real-time tasks, and several algorithms
are also examined to check the schedulability of a given strategy. An approach
is then proposed based on the schedulability condition to adapt a
continuous-speed-based method to a discrete-speed system. The approach is able
to stay as close as possible to the continuous-speed-based method, but still
guaranteeing the schedulability. It is shown by simulations that the energy
saving can be more than 20% for some system configurationsComment: 10 page
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