Diamonds are a quantum scientist's best friend
The discovery of triplet spin superconductivity in diamonds has the
potential to revolutionise the high-tech industry.

Date:
October 7, 2020
Source:
University of the Witwatersrand
Summary:
New research details the phenomenon of what is called 'triplet
superconductivity' in diamond. Triplet superconductivity occurs
when electrons move in a composite spin state rather than as a
single pair.

This is an extremely rare, yet efficient form of superconductivity
that until now has only been known to occur in one or two other
materials, and only theoretically in diamonds.



FULL STORY ========================================================================== Diamonds have a firm foothold in our lexicon. Their many properties often
serve as superlatives for quality, clarity and hardiness. Aside from
the popularity of this rare material in ornamental and decorative use,
these precious stones are also highly valued in industry where they are
used to cut and polish other hard materials and build radiation detectors.


==========================================================================
More than a decade ago, a new property was uncovered in diamonds when
high concentrations of boron are introduced to it -- superconductivity.

Superconductivity occurs when two electrons with opposite spin form a
pair (called a Cooper pair), resulting in the electrical resistance of
the material being zero. This means a large supercurrent can flow in
the material, bringing with it the potential for advanced technological applications. Yet, little work has been done since to investigate and characterise the nature of a diamond's superconductivity and therefore
its potential applications.

New research led by Professor Somnath Bhattacharyya in the Nano-Scale
Transport Physics Laboratory (NSTPL) in the School of Physics at
the University of the Witwatersrand in Johannesburg, South Africa,
details the phenomenon of what is called "triplet superconductivity"
in diamond. Triplet superconductivity occurs when electrons move in a
composite spin state rather than as a single pair.

This is an extremely rare, yet efficient form of superconductivity that
until now has only been known to occur in one or two other materials,
and only theoretically in diamonds.

"In a conventional superconducting material such as aluminium, superconductivity is destroyed by magnetic fields and magnetic impurities, however triplet superconductivity in a diamond can exist even when
combined with magnetic materials. This leads to more efficient and multifunctional operation of the material," explains Bhattacharyya.

The team's work has recently been published in an article in the New
Journal of Physics, titled "Effects of Rashba-spin-orbit coupling on superconducting boron-doped nanocrystalline diamond films: evidence
of interfacial triplet superconductivity." This research was done in collaboration with Oxford University (UK) and Diamond Light Source
(UK). Through these collaborations, beautiful atomic arrangement of
diamond crystals and interfaces that have never been seen before could
be visualised, supporting the first claims of 'triplet' superconductivity.

Practical proof of triplet superconductivity in diamonds came with much excitement for Bhattacharyya and his team. "We were even working on
Christmas day, we were so excited," says Davie Mtsuko. "This is something
that has never been before been claimed in diamond," adds Christopher
Coleman. Both Mtsuko and Coleman are co-authors of the paper.

Despite diamonds' reputation as a highly rare and expensive resource,
they can be manufactured in a laboratory using a specialised piece
of equipment called a vapour deposition chamber. The Wits NSTPL has
developed their own plasma deposition chamber which allows them to grow diamonds of a higher than normal quality -- making them ideal for this
kind of advanced research.

This finding expands the potential uses of diamond, which is already
well- regarded as a quantum material. "All conventional technology is
based on semiconductors associated with electron charge. Thus far,
we have a decent understanding of how they interact, and how to
control them. But when we have control over quantum states such as superconductivity and entanglement, there is a lot more physics to the
charge and spin of electrons, and this also comes with new properties,"
says Bhattacharyya. "With the new surge of superconducting materials
such as diamond, traditional silicon technology can be replaced by
cost effective and low power consumption solutions." The induction of
triplet superconductivity in diamond is important for more than just its potential applications. It speaks to our fundamental understanding of
physics. "Thus far, triplet superconductivity exists mostly in theory,
and our study gives us an opportunity to test these models in a practical
way," says Bhattacharyya.


========================================================================== Story Source: Materials provided by University_of_the_Witwatersrand. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Somnath Bhattacharyya, Davie Mtsuko, Christopher Allen, Christopher
Coleman. Effects of Rashba-spin-orbit coupling on superconducting
boron- doped nanocrystalline diamond films: evidence of interfacial
triplet superconductivity. New Journal of Physics, 2020; 22 (9):
093039 DOI: 10.1088/1367-2630/abafe9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201007123059.htm

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