Fifty years ago, no one even understood why this phenomena existed at all. We are at least past that and are now learning how nature engineers it into materials. We have even reached room temperature for particularly exotic complexes.
I do suspect that we will ultimately produce an active multi layered skin able to internally generate super conductance at a useful operating temperature and then leading to the UFO engineering that we see in our skies.
This report establishes that we are slowly learning to work at the scales necessary.
New Superconducting States Have Been Discovered
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November 12, 2019
November 12, 2019
Superconductivity has been shown in monolayer crystals of, for example,
molybdenum disulphide or tungsten disulfide that have a thickness of
just three atoms. ‘In both monolayers, there is a special type of
superconductivity in which an internal magnetic field protects the
superconducting state from external magnetic fields,’ Ye explains.
Normal superconductivity disappears when a large external magnetic field
is applied, but this Ising superconductivity is strongly protected.
Even in the strongest static magnetic field in Europe, which has a
strength of 37 Tesla, the superconductivity in tungsten disulfide does
not show any change. However, although it is great to have such strong
protection, the next challenge is to find a way to control this
protective effect, by applying an electric field.
Ionic liquid
Ye and his collaborators studied a double layer of molybdenum
disulfide: ‘In that configuration, the interaction between the two
layers creates new superconducting states.’ Ye created a suspended
double layer, with an ionic liquid on both sides that can be used to
create an electric field across the bilayer. ‘In the individual
monolayer, such a field will be asymmetric, with positive ions on one
side and negative charges induced on the other. However, in the bilayer,
we can have the same amount of charge induced at both monolayers,
creating a symmetrical system,’ Ye explains. The electric field that was
thus created could be used to switch superconductivity on and off. This
means that a superconducting transistor was created that could be gated
through the ionic liquid.
In the double layer, the Ising protection against external magnetic
fields disappears. ‘This happens because of changes in the interaction
between the two layers.’ However, the electric field can restore the
protection. ‘The level of protection becomes a function of how strongly
you gate the device.’
Conceptual changes
Apart from creating a superconducting transistor, Ye and his
colleagues made another intriguing observation. In 1964, a special
superconducting state was predicted to exist, called the FFLO state
(named after the scientists who predicted it: Fulde, Ferrell, Larkin and
Ovchinnikov). In superconductivity, electrons travel in pairs in
opposite directions. Since they travel at the same speed, these Cooper
pairs have a total kinetic momentum of zero. But in the FFLO state,
there is a small speed difference and therefore the kinetic momentum is
not zero. So far, this state has never been properly studied in
experiments.
‘We’ve met nearly all the prerequisites to prepare the FFLO state in
our device,’ says Ye. ‘But the state is very fragile and is
significantly affected by contaminations on the surface of our material.
We will therefore need to repeat the experiments with cleaner samples.’
With the suspended bilayer of molybdenum disulfide, Ye and
collaborators have all the ingredients needed to study some special
superconducting states. ‘This is truly fundamental science that might
bring us conceptual changes.’
Superconductivity in monolayer transition metal dichalcogenides is
characterized by Ising-type pairing induced via a strong Zeeman-type
spin–orbit coupling. When two transition metal dichalcogenides layers
are coupled, more exotic superconducting phases emerge, which depend on
the ratio of Ising-type protection and interlayer coupling strength.
Here, we induce superconductivity in suspended MoS2 bilayers and unveil a
coupled superconducting state with strong Ising-type spin–orbit
coupling. Gating the bilayer symmetrically from both sides by ionic
liquid gating varies the interlayer interaction and accesses electronic
states with broken local inversion symmetry while maintaining the global
inversion symmetry. We observe a strong suppression of the Ising
protection that evidences a coupled superconducting state. The symmetric
gating scheme not only induces superconductivity in both atomic sheets
but also controls the Josephson coupling between the layers, which gives
rise to a dimensional crossover in the bilayer.
SOURCES – Nature Nanotechnology, University of Groningen
Written by Brian Wang, Nextbigfuture.com
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