The team of Nobel laureate Andre Geim from the University of Manchester has made a new discovery related to graphene. Scientists have shown that this form of carbon, like no other material, is able to change its resistance in an external magnetic field and at room temperature, according to the study. published in the journal Nature.
In 2010, the Nobel Prize in Physics was awarded to MIPT graduates Andrey Geim and Konstantin Novoselov for the first practical production of graphene, a two-dimensional form of carbon with many useful properties.
Since then, Andrey Geim, who works at the University of Manchester, has continued to study graphene, discovering new and unusual characteristics of this material.
The new discovery by Geim’s team is associated with a physical property of certain materials such as magnetoresistance. This phenomenon consists in the ability to change its electrical resistance under the influence of an external magnetic field.
Scientists have long been looking for compounds capable of significantly changing the resistance in a magnetic field – such materials are needed in various technological fields. In every modern car and computer there are magnetic sensors that work on this effect. However, materials with very high magnetoresistance are rare – as a rule, most metals and semiconductors at room temperature, under the influence of a magnetic field, change their resistance only by a fraction of a percent . Therefore, to observe strong magnetoresistance, scientists typically cool materials to the temperature of liquid helium.
Now, scientists led by Game have shown that high magnetoresistance is demonstrated by “good old” graphene, which has been studied in detail over the past two decades. “People like me who work with graphene always feel like this gold mine of physics should have dried up a long time ago. But this material continues to prove us wrong, discovering new incarnations every time. Today, I am again forced to admit that graphene is dead, long live graphene,” the scientist said.
In experiments, Game and his colleagues introduced graphene to a special state in which a plasma is created in it from the so-called Dirac fermions, which demonstrate high mobility. This property of these particles and the neutrality of the plasma are the main reasons for the demonstrated high magnetoresistance. In the experiments, the resistance increased by 100% in the fields of ordinary permanent magnets with an induction of 0.1 Tesla at room temperature. According to scientists, such magnetoresistance is a record for all materials known to science.
“Over the past 10 years, the electronic quality of graphene devices has increased dramatically, and everyone is looking to find new low-temperature effects of liquid helium, not noticing what happens at room temperature. This n “is not surprising, because the colder your sample, the more interesting it usually behaves. We decided to increase the temperature and suddenly we are faced with an abundance of new effects,” explained co-author Alexei Berdyugin. of the study.
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