Graphene is a unique substance. Among its various abilities, it can produce
a super-rare kind of magnetism, operate as a superconductor, and open up
completely new quantum states.
Another incredible feature of graphene is that it can measure
magnetoresistance levels without requiring temperatures to drop below
absolute zero.
While being relatively uncommon, materials with high magnetoresistance—the
capacity to alter its electrical resistance in reaction to a magnetic
field—are helpful in computers, automobiles, and medical equipment.
Ultra-low temperatures often provide the most intriguing graphene behavior
and, in fact, the greatest amounts of magnetoresistance.
In this most recent experiment, scientists from the Universities of
Manchester and Lancaster in the United Kingdom subjected premium graphene to
magnetic fields at room temperature and evaluated its reaction.
According to materials scientist Alexey Berdyugin from the University of
Manchester, "Over the last ten years, electronic quality of graphene devices
has improved dramatically, and everyone seems to focus on finding new
phenomena at low, liquid-helium temperatures, ignoring what happens under
ambient conditions."
As we increased the temperature, a wide range of unanticipated occurrences
appeared.
To ensure that only temperature might affect graphene's conductivity, the
researchers employed a pure and unaltered version of the material. By
jumping about, charged particles that are excited by a rise in temperature
reveal gaps or "holes" in the material.
The heated graphene had a magnetoresistance response more than 100% when
subjected to conventional permanent magnets, breaking the previous record
for any material. To put that reaction into perspective, most metals and
semiconductors barely vary their electrical resistance by a tiny fraction of
1% at ambient temperature and under actual magnetic fields.
According to the researchers, it depends on the mobility and equilibrium of
the negatively charged electrons and the positively charged holes left
behind when the electrons travel.
According
to scientist Leonid Ponomarenko of Lancaster University in the UK, "Undoped
high-quality graphene at room temperature gives a chance to investigate a
totally new regime that in theory might have been discovered even a decade
ago but was somehow neglected by everyone."
We intend to investigate this strange-metal domain, and inevitably, other
intriguing findings, occurrences, and applications will come.
The experiment had another intriguing result, too. The undamaged graphene
transformed into an unidentified sort of substance known as a "weird metal"
as the temperature rose.
What we do know about these metals is that they behave in unexpected ways,
and graphene was no exception in this case. The connection between
temperature and electrical resistance, in particular, is different from what
is seen in typical metals.
Although the discovery has no obvious applications in the real world, it
considerably advances our knowledge of how materials and their physics
function. It also highlights how unique and useful graphene is.
Scientist Andre Geim from the University of Manchester
says, "Those working on graphene like myself always believed that this goldmine
of physics should have been drained long ago."
"The material continues to contradict us, appearing in yet another form.
Today I must one more declare that graphene is extinct and long live
graphene.
The research has been published in
Nature.
