Electronic Structure of Three-Dimensional Superlattices Subject to Tilted Magnetic Fields

Full quantum-mechanical description of electrons moving in 3D structures with unidirectional periodic modulation subject to tilted magnetic fields requires an extensive numerical calculation. To understand magneto-oscillations in such systems it is in many cases sufficient to use the quasi-classical approach, in which the zero-magnetic-field Fermi surface is considered as a magnetic-field-independent rigid body in k-space and periods of oscillations are related to extremal cross-sections of the Fermi surface cut by planes perpendicular to the magnetic-field direction. We point out cases where the quasi-classical treatment fails and propose a simple tight-binding fully-quantum-mechanical model of the superlattice electronic structure.Comment: 8 pages, 7 figures, RevTex, submitted to Phys. Rev.

Angular magnetoresistance oscillations in bilayers in tilted magnetic fields

Angular magnetoresistance oscillations (AMRO) were originally discovered in organic conductors and then found in many other layered metals. It should be possible to observe AMRO to semiconducting bilayers as well. Here we present an intuitive geometrical interpretation of AMRO as the Aharonov-Bohm interference effect, both in real and momentum spaces, for balanced and imbalanced bilayers. Applications to the experiments with bilayers in tilted magnetic fields in the metallic state are discussed. We speculate that AMRO may be also observed when each layer of the bilayer is in the composite-fermion state.Comment: 4 pages, 5 figures, Proceedings of EP2DS-16. V.2: figures corrected, one reference added. V3: one reference adde

Modeling Software Characteristics and Their Correlations in A Specific Domain by Comparing Existing Similar Systems

QSIC 2005, Melbourne, Australia, Sep. 2005Software in a specific domain has several characteristics and each characteristic should be fixed when the software requirements are specified. In addition, these characteristics sometimes correlate with each other. However, we sometimes forget to specify several characteristics and/or to take their correlations into account during requirements elicitation. In this paper, we propose a meta-model for representing such characteristics and their correlations, and also propose a method to build a model for a specific domain by using documents about existing software systems. By using our model for a domain, a requirements specification for a system in the domain could be complete and unambiguous because requirements analysts can check the characteristics that should be decided. The specification could be also correct and consistent because the analysts can know side effects of a requirement change by using correlation among the characteristics. We have applied our methods to a case study for confirming the usefulness of such model and the methods.ArticleProceedings : the Fifth International Conference on Quality Software. 215-222 (2005)conference pape

Possible Verification of Tilted Anisotropic Dirac Cone in \alpha-(BEDT-TTF)_2 I_3 Using Interlayer Magnetoresistance

It is proposed that the presence of a tilted and anisotropic Dirac cone can be verified using the interlayer magnetoresistance in the layered Dirac fermion system, which is realized in quasi-two-dimensional organic compound \alpha-(BEDT-TTF)_2 I_3. Theoretical formula is derived using the analytic Landau level wave functions and assuming local tunneling of electrons. It is shown that the resistivity takes the maximum in the direction of the tilt if anisotropy of the Fermi velocity of the Dirac cone is small. The procedure is described to determine the parameters of the tilt and anisotropy.Comment: 4 pages, 4 figures, corrected Fig.

Magic angle effects of the one-dimensional axis conductivity in quasi-one dimensional conductors

In quasi-one-dimensional conductors, the conductivity in both one-dimensional axis and interchain direction shows peaks when magnetic field is tilted at the magic angles in the plane perpendicular to the conducting chain. Although there are several theoretical studies to explain the magic angle effect, no satisfactory explanation, especially for the one-dimensional conductivity, has been obtained. We present a new theory of the magic angle effect in the one-dimensional conductivity by taking account of the momentum-dependence of the Fermi velocity, which should be large in the systems close to a spin density wave instability. The magic angle effect is explained in the semiclassical equations of motion, but neither the large corrugation of the Fermi surface due to long-range hoppings nor hot spots, where the relaxation time is small, on the Fermi surface are required.Comment: 4 pages, 3 figure

Facial reanimation by transposition of the masseter muscle combined with tensor fascia lata, using the zygomatic arch as a pulley

This is an electronic version of an article published in Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 42(1):17-22 (2008). Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery is available online at informaworldTM.ArticleScandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. 42(1):17-22 (2008)journal articl