Closing in on superconductivity

1993 
S/D Microwave penetration depths
S/D Photoemission
D wave SQUIOD Interferometry

1994 
D-w SQUID Interferometry
S Tricrystal ring magnetometry
S Grain boundary tunneling
S C-axis tunneling
1996 
D Tricrystal ring magnetometry

    /*---------------------------------------------------------------------*/
 
Blue Laser Race Turns Red-Hot

In the race to make the first blue light semiconductor
lasers, the lead horse has come up slightly lame.
chip based lasers ... Zinc-selenide (ZnSe)

A robust semicondutor alloy known as gallium nitride (GaN) report 
sent a ripple of excitement.

The whole world has been trying to make a GaN laser diode.
It can be done.

GaN is already used to make other light emitters, (LEDs).  This
will push a GaN Laser to the head of the field.  Quadrupling
the storage capacity of devices that currently
use longer wavelength red lasers.  Such as
optical computer discs and audio compact discs.

    /*---------------------------------------------------------------------*/
 
Interfering with atoms to clear a path for lasers

Laser passing through transparent medium such as air.
Weak lasers slip through without difficulty,
but more intense beams run into trouble.  
Use the second laser beam
to put a kind of EM lock on the atoms of the medium
so that their optical properties
can't change.  Self focusing psrings .
phenomenon EM induced transparency.  Allows a lser beam
to pass undimmed through an otherwise opaque medium.   Each atom
has an electron that oscillates from its
ground state to a higher energy state, known as the
resonant energy, when it feels the laser's
oscillating electric field.
An atom see 1 electron moving back and forth 
periodically at the frequency of the light.
In an opaque medium these electrons oscillate out of phase with the
light.  And the beam quickly loses
energy and is absorbed.
A second laser quantum mechanically freeze
the electrons by setting up two possible
routes of excitation to the higher energy state.

    /*---------------------------------------------------------------------*/
 
Microscopic Tunneling Sectroscopy on High Temperature Superconductors

Tunneling spectroscopy crucial to BCS mechanism in superconductors
Cryogenic scanning tunneling microscopy (STM) 
local tunneling spectroscopy to discriminate
among the relative contributions to superconductivity from each
of the atomic positions in the superconducting
crystal structure. 


    /*---------------------------------------------------------------------*/
 
Cellular Microbiology Emerging

Yersinia
Helicobacter Pylori
VacA Toxin
Trypanosoma
Salmonella
Membrane Ruffling
Filopodia
ActA CAAX
Mycobacterium tuberculosis
Listeria Monocytogenes
Clostridial Toxins
Neurotoxins

    /*---------------------------------------------------------------------*/
 
Pairing Symmetry in Single Layer tetragonal Tl2Ba2CuO6+/\
A high resolution scaning superconducting quantum
interference device microscopy study of tetragonal
single layer Tl2Ba2CuO6 films, deposited on
tricrystal SrTiO3 substrates, demonstrates
the effect of spontaneously generated half flux
quanta.  This observation shows that in addition to YBa2Cu3O7 the order parameter
symmetry in Tl2Ba2CuO6 is consistent with that
of a dx2-y2 pair state.  This result also 
reuls out ay bilayer of twinning effects and any pairing that is incompatible
with the fourfold rotational symmetry as in the Tl2Ba2CuO6 superconducting system.

    /*---------------------------------------------------------------------*/
 
Chaos and shapes of Elliptical Galaxies
Hubble space telescope observations reveal that the density
of stars in most elliptical galaxies rises toward the center in a power-law
cusp.  Many of these galaxies also contain central dark objects,
possibly supermassive black holes.  The gravitational
force from a steep cusp or black hole will destroy most of the box orbits
that constitute the
"backbone" of a triaxial stellar system.  Detailed modeling demonstrates that
the resulting chaos can preclude a self-consistent, strongly triaxial
equilibrium.  Most elliptical 
galaxies may therefore be nearly axisymmetric, either oblate or prolate.



--fin