Technion team frees individual oxygen atoms

A research team from Israel’s Technion University, Israel’s leading research institution, has succeeded in changing the electrical properties of a material by removing a single oxygen atom from the original structure.
the study, which was published in the peer-reviewed scientific journal ACS Nano, shares findings that are a potential advance in the study and development of ferroelectric materials. Ferroelectric materials, such as barium titanate and Rochelle’s salt, are characterized by a strong correlation between their atomic structure and their electrical and mechanical properties. They are essential for the development of electronic devices.

The researchers used barium titanate, whose atoms form a cubic lattice structure, for the study. In ferroelectric materials, a unique phenomenon occurs: titanium atoms move away from oxygen atoms, since titanium is positively charged and oxygen is negatively charged.

A cubic lattice has six faces, so the charged atoms move to one of six possibilities. In different parts of the material, a large number of neighboring atoms move in the same direction, and the polarization in each of those areas, known as ferroelectric domains, is standard and uniform. Traditional technologies are based on the electric field created in those domains.

Ferroelectric materials side by side after removing the oxygen atom. (credit: TECHNION)

In recent years, however, a lot of effort has gone into minimizing device size and using borders, or walls, between domains rather than the domains themselves.

The research community has remained divided in opinion about what happens in the two-dimensional world of domain walls: How is the boundary between two domains with different electrical polarization stabilized? Is the polarization in the domain walls different from the polarization in the domains themselves? Can domain wall properties be controlled locally?

While ferroelectric materials are excellent at conducting electricity, the domain’s walls form a two-dimensional object that is controllable at the will of scientists. This phenomenon encompasses the potential to significantly reduce power consumption between data storage and processing devices.

The researchers finally managed to ingeniously induce a single oxygen atom vacancy and showed that this action creates opposing dipoles and greater electrical symmetry, a unique topological structure called a quadrupole.

The findings showed that designing an oxygen atom vacancy has a major impact on the electrical properties of the material, not only at the atomic scale, but also at the scale that is relevant to electronic devices, for example in terms of electrical conductivity. The findings will help reduce the power consumption of electronic devices.

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