This is the crystal structure of Nb3SiTe6.
Credit: Copyright J. Hu et al/ Nature Physics
Scientists from the MIPT Department of
Molecular and Chemical Physics have for the first time described the
behavior of electrons in a previously unstudied analogue of graphene,
two-dimensional niobium telluride, and, in the process, uncovered the
nature of two-dimensionality effects on conducting properties. These
findings will help in the creation of future flat and flexible
electronic devices.
In recent decades, physicists have been actively studying so-called
two-dimensional materials. Andrei Geim and Konstantin Novoselov received
the Nobel Prize for their research on graphene, the most well-known
among them. The properties of such materials, which can be described as
"sheets" with a thickness of a few atoms, strongly differ from their
three-dimensional analogues. For example, graphene is transparent,
conducts current better than copper and has good thermal conductivity.
Scientists believe that other types of two-dimensional materials may
possess even more exotic properties.
A group of scientists from Russia and the USA, including Pavel
Sorokin and Liubov Antipina from MIPT, recently conducted research on
the properties of the crystals of one such material,Nb3SiTe6, a compound
of niobium telluride. In their structure, the crystals resemble
sandwiches with a thickness of three atoms (around 4 angstroms): a layer
of tellurium, a layer of niobium mixed with silicon atoms and then
another layer of tellurium. This substance belongs to a class of
materials known as dichalcogenides, which many scientists view as
promising two-dimensional semiconductors.
The scientists synthesized Nb3SiTe6 crystals in a laboratory at
Tulane University (New Orleans). They then separated them into
two-dimensional layers, taking samples for further analysis by
transmission electron microscopy, X-ray crystal analysis and other
methods. The goal of the researchers was to investigate electron-phonon
interaction changes in two-dimensional substances.
Quasi particles, quanta of crystal lattice oscillations, are called
phonons. Physicists introduced the concept of phonons because it helped
simplify the description of processes in crystals, and tracking of
electron-phonon interaction is fundamentally important for description
of the different conducting properties in matter.
"We developed a theory that predicts that electron-phonon interaction
is suppressed due to dimensional effects in two-dimensional material.
In other words, these materials obstruct the flow of electrons to a
lesser extent," says Pavel Sorokin, a co-author of the study, doctor of
physical and mathematical sciences, and lecturer at the MIPT Section of
the Physics and Chemistry of Nanostructures (DMCP).
American colleagues confirmed this prediction in related experiments.
"They conducted measurements where the same effect was observed. Our
calculations allowed the ruling out of other explanations; we managed to
prove that changes in electron-phonon interaction occur specifically
because of the two-dimensionality of the membrane," Sorokin adds.
Story Source:
The above post is reprinted from
materials provided by
Moscow Institute of Physics and Technology.
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