A Molecular Paramagnetic Superconductor

Superconductors consisting of molecular solids (vs metals) are essential 
to many applications.  It has long been thought that the presence of 
magnetic ions in the molecular structure should decrease or even suppress 
superconductivity.  Kurmoo prepared and characterized the first example 
of a molecular superconductor containing iron magnetic anions.  These 
results contradict our preconceived notions about the coexistence of 
magnetism and superconductivity and systems exhibiting interaction between 
conduction electrons and localized spins.

    Most molecular superconductors are electron-transfer salts of the 
type (BEDT-TTF)2A, where BEDT-TTD is bis(ethylenedithio) tetrathiafulvalene 
and A is a counteranion.  The anion A may be octahedral (such as PF6, 
tetrahedral (ClO4) , linear (I3) or polymeric (CuNCS2).  The highest 
superconducting critical temperature Tc observed to date for a molecular 
superconductor is 12.8K in the k-(BEDT-TTF)2(CuNCN2Cl phase.  In none of 
these molecule based superconducting salts is the counter anion A magnetic; 
that is, none of these salts contains localized anion spins.

    The application of a magnetic field suppress superconductivity the 
Meissner effect.  as do internal magnetic fields generated in ferromagnetic 
materials.  This effect may be understood within the framework of the 
Bardeen-cooper-schrieffer theory (BCS) for 3D systems exhibiting a spherical 
Fermi surface.  According to BCS theory, the occurrence of singlet-state 
superconductivity results from the pairing of electrons having opposite spins.
(Cooper pairs).  This pairing is mediated by lattice vibrations and can be 
disrupted by the close vicinity of magnetic impurities.  These impurities 
must only be sufficiently diluted, paramagnetic and thus without either 
short or long range magnetic order.  For example, few PPM of iron prevent 
molybdenum from becoming superconducting; this observation has been also 
made for the commonly used superconducting alloys of transition metals.


    Several attempts have been made to couple interesting conducting and 
magnetic behaviors in a molecular compound.  A first example was given by 
[TTF]Mx4C4CF3)4 compounds (M=Cu,Au;X=S,Se) which exhibit low conductivities 
but undergo a unique , so called spin-Peierls, second-order transition at 
low temperatures to a nonmagnetic state.  The 2,5-XY-DCNQI]2Cu compounds 
(DCNQI=N,N' dicyanoquinone diimine; X,Y=Me,Cl,Br) were shown to exhibit 
metallic properties down to low temperatures and a ferromagnetic ordering 
of the copper spins.  In the perelene)2[M(mnt)2] compounds (M=transition 
metal;mnt=maleonitriledithiolate, [C4N2S2]2--), instabilities typical of 
one-dimensional conducting(Peierls instability, for the perylene chains)
and magnetic [spin Peierls instability, for the M(mnt)2 chains] systems 
were observed.


    The first examples of BEDT-TTF based metals with magnetic anions FeX4 
and CuX4 have been reported by Day et al.  Although these materials did 
exhibit interesting conducting and magnetic properties, none of them showed 
superconducting behavior.

The Meissner effect is complete at 0.5mT .  The electron paramagnetic resonance 
spectra show one Dysonian in shape resonance due to the conduction electrons 
of the BEDT-TTF chains and one Lorentzian in shape resonance due to the 
Fe3+ ions.  Electronic band structure calculations based on crystal data
obtains at 300K confirm a metallic behavior with both electron and hole 
pockets in the fermi surface.  This phase truly is the first molecule based 
paramagnetic superconductor.


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Near-Term

Men : Stopping sperm production with injections of 
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Women : Inducing menses with a combination of antiprogestins, antiestrogens,
inhibitors of enzymes involved in steroid synthesis

Medium Term

Women : Preventing sperm passage by modifying
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Long Term
Men : Preventing sperm maturation by
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Men : Preventing fertilization by causing
sperm cells to prematurely release enzymes that otherwise break
through the eggs protective coat

Women : 
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Women :
Preventing fertilization of the implantation
of a fertilized egg in the 
uterine lining with various vaccines.