Scientists from the University of MISIS and the Kurchatov Institute Research Center have improved the technology for producing ultra-thin wires for the production of non-volatile microcircuits, medical sensors, and sensory devices. This approach makes it possible to regulate the composition of the alloy without selecting electrolytes - this provides more predictable, reproducible results and, in the future, will reduce the consumption of expensive components.
Dinara Khairetdinova
Electronics needs materials whose properties can be precisely adjusted: they must maintain magnetization and quickly respond to changes in the external field. Scientists have proposed an alloy consisting of three metals with adjustable parameters: iron in combination with cobalt or nickel has strong magnetism, and copper controls a number of characteristics.
"One of the tasks of the University of MISIS is to ensure the creation of materials with a combination of properties necessary for their practical use in production. Our researchers, under the guidance of Professor Larisa Panina, have been developing functional magnetic micro- and nanowires for sensors, smart materials and biomedicine for a number of years. The proposed solution will make it possible to control the magnetic properties of ultra-thin wires, which is important in the development of technologies for the production of sensors for use in electronics, radio electronics and medicine, industrial chemistry devices, electromagnetic shielding and a new generation of logic," said Alevtina Chernikova, Rector of NUST MISIS.
"Copper affects the magnetic properties, phase composition and crystalline structure of the alloy. When it is added, additional phases are formed - for example, FeCu and NiCu - which changes the distribution of magnetic elements in the material. This, in turn, affects the magnetic anisotropy and the angles of inclination of the magnetic moments, which affects the coercive force and stability," — shared Dinara Khairetdinova, a laboratory researcher at the Laboratory of Intelligent Sensor Systems at NUST MISIS.
Scientists deposited metal atoms through microscopic holes in a polymer matrix - this is how threads are formed a thousand times thinner than a human hair. By changing the voltage, you can control the composition of alloys: the proportion of copper and the ratio of iron to cobalt and nickel.
Researchers have proven that copper increases the alloy's resistance to demagnetization. For example, wires made of iron, cobalt and 6% copper retained magnetization under an external influence of 370 Oersted - this is several percent higher than in traditional two-component systems. For iron, nickel and 9% copper, the best result is 275 Oersted. Detailed results are described in the scientific journal Crystallography Reports.
Professor of the Department of Electronic Materials Technology of NUST MISIS, Doctor of Physics and Mathematics Larisa Panina said that in cobalt alloys, iron is deposited faster at low voltage, and the ratio is equalized when the voltage is increased. In alloys where nickel is used instead of cobalt, the situation is different: at high voltage, the proportion of iron in the alloy increases significantly.
"Thus, changing the voltage allows you to regulate not only the amount of copper, but also the ratio between iron and magnetic metal. The difference between these phases affects the magnetic characteristics of the material, which allows you to give the wires the necessary properties at the deposition stage," — added Larisa Panina.
The work was supported by the Russian Science Foundation (project No. 22-22-00983).
