88 research outputs found
Transport Signatures of Fermi Surface Topology Change in BiTeI
We report a quantum magnetotransport signature of a change in Fermi surface
topology in the Rashba semiconductor BiTeI with systematic tuning of the Fermi
level . Beyond the quantum limit, we observe a marked increase/decrease in
electrical resistivity when is above/below the Dirac node that we show
originates from the Fermi surface topology. This effect represents a
measurement of the electron distribution on the low-index () Landau
levels and is uniquely enabled by the finite bulk dispersion along the
-axis and strong Rashba spin-orbit coupling strength of the system. The
Dirac node is independently identified by Shubnikov-de Haas oscillations as a
vanishing Fermi surface cross section at . Additionally we find that the
violation of Kohler's rule allows a distinct insight into the temperature
evolution of the observed quantum magnetoresistance effects.Comment: 12 pages, 4 figure
A quantum chemical study of the retinal of squid rhodopsin
The squid retinal structure obtained from the Protein Data Bank (PDB ids 2Z73 and 2ZIY) is studied in a quantum chemistry method using MOPAC2009 based on a semi-empirical method with PM6 parametrization. The interaction between retinal and light (an electromagnetic field) is effectively described by the interaction between dipoles and electromagnetic fields. Thus we investigated the dipole moment and effective charge distribution of retinal. We also looked at molecular orbitals, especially the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital). MO shifting between a double bonded site and single bonded site is seen by comparing HOMO and LUMO results. Retinal changes its conformation from cis to trans at carbon 11. This carbon's effective charge is very small so that it is free from electric interactions. Then it can change conformation with a small change in energy
Effects of Water Molecules on Lipid Bilayer Dynamics in Aqueous Salt Solutions:Analyses of Molecular Dynamics Simulation
Thermodynamic determination of the equilibrium first-order phase-transition line hidden by hysteresis in a phase diagram
Phase diagrams form the basis for the study of material science, and the
profiles of phase-transition lines separating different thermodynamic phases
include comprehensive information about thermodynamic quantities, such as
latent heat. However, in some materials exhibiting field-induced first-order
transitions (FOTs), the equilibrium phase-transition line is hidden by the
hysteresis region associated with the FOT; thus, it cannot be directly
determined from measurements of resistivity, magnetization, etc. Here, we
demonstrate a thermodynamics-based method for determining the hidden
equilibrium FOT line. This method is verified for the FOT between
antiferromagnetic and ferrimagnetic states in magneto-electric compounds
(FeZn)MoO. The equilibrium FOT line
determined based on the Clausius-Clapeyron equation exhibits a reasonable
profile in terms of the third law of thermodynamics, and it shows marked
differences from the midpoints of the hysteresis region. Our findings highlight
that care should be taken for referring to the hysteresis midpoint line when
discussing field-induced latent heat or magnetocaloric effects.Comment: 22 pages, 7 figure
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