Science & Technology, UK (Commonwealth Union) – Recent findings from the University of Birmingham reveal a strong correlation between the electronic structure of metals and their mechanical characteristics.
Published in the Science journal on October 26th, this groundbreaking research marks the first experimental demonstration of the interconnection between a metal’s electronic and mechanical attributes. Previously, it had been theorized that such a connection existed, but it was believed to be too minuscule to detect in practical experiments.
Dr Clifford Hicks, Reader in Condensed Matter Physics, who was engaged in the study says “Mechanical properties are typically described in terms of the bonding between atoms, while electronic properties of metals are described by states that extend across many atoms. The atomic lattice (the term used to describe the arrangement of atoms) of a metal and its mechanical properties are generally thought of as being unaffected by which electronic states are occupied and which are empty, but in this work, we show that this is not always a good assumption.”
Collaborating with researchers from the University of Birmingham, scientists from the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, conducted experiments on the superconducting metal strontium ruthenate (Sr2RuO4). Their investigation involved measuring lattice distortion in response to applied stress. The team observed that as Sr2RuO4 was compressed by approximately 0.5%, the Young’s modulus, a measure of mechanical stiffness, decreased by about 10%. Subsequently, with further compression, it increased by roughly 20%. This transition corresponded to the occupation of a new set of electronic states, a phenomenon previously identified through electronic measurements but not in terms of mechanical properties.
Dr Hicks further expressed his views saying “Whilst it is completely standard to measure stress-strain relationships in mechanical engineering, it is not something that has been done to study electronic properties. This is because the metals that have interesting electronic properties tend to be brittle, making it hard to apply large forces. Also, large strains are typically required to meaningfully alter electronic properties. In this experiment, samples of Sr2RuO4 were compressed by up to 1%. To visualise that, imagine taking a metrestick made of granite, and squeezing it until it is 99 cm long.”
Sr2RuO4 is the chemical formula of Strontium ruthenate which is a complex oxide material. It is composed of strontium (Sr), ruthenium (Ru), and oxygen (O) atoms arranged in a crystalline lattice structure. The compound, stands as a shining gem—a material that has captured the attention of scientists and researchers around the world. This remarkable compound, a member of the perovskite family of oxides, possesses unique properties that make it a subject of intense study and curiosity.
To surmount these challenges, the researchers had to create novel instrumentation capable of measuring small and delicate samples while operating at cryogenic temperatures, as electronic measurements exhibit greater accuracy at lower temperature levels. The planning and design phase alone required five years of dedicated effort.
This groundbreaking study, financially supported by the German Research Foundation (Deutsche Forschungsgemeinschaft) and the Max Planck Society, stands as the pioneer in its field.
With the successful completion of this experiment on a single material, the scientists are eager to extend similar measurements to other metals. A version of the equipment developed for this project has been produced by a U.K.-based engineering company, and as the device undergoes further refinement, it may find applications in the examination of high-strength alloys. Researchers of the study pointed out that this project serves as an illustrative example of how fundamental research driven by curiosity can ultimately lead to the development of new technologies with practical uses. Most often it is this curiosity in science that drives innovation.
