JS Communications Skills – Task 7:
Physics Blog Post
By May Taylor
“Not only is the Universe stranger than we think, it is stranger than we can think.”
Scientists are deeply invested in the next generation of quantum materials, searching any uncharted classes of enigmatic materials to exploit in the creation of new, innovative technology. One such candidate, known as the ‘strange’ metals, are catching the eye of researchers, particularly the compound YbAlB4, made of the elements ytterbium, aluminium and boron, affectionately known as ‘Y-Ball’.
What’s so Special about these Metals?
Strange metals are so called as their behaviour drastically deviates from the familiar properties of metals. They do not obey the standard electrical conventions, they share mysterious similarities to black holes and they challenge and contradict elements of Quantum Theory.
1. Their resistance increases linearly with temperature. In normal metals, the resistance increases until it plateaus, becoming constant at high temperatures in accord with Fermi liquid theory, a model composed of interacting fermions in a low temperature system, which describes the normal state of most metals. Resistance in metals arises when the flow of free electrons is hindered in some way, by the vibrating atomic structure of the material or through collisions with other electrons, leading to electron scattering. Fermi-liquid theory dictates a maximum rate at which the scattering of these electrons can occur. But strange metals don’t follow the Fermi-liquid rules, puzzling material scientists around the world.
2. Strange metals are high-temperature superconductors, with negligible resistance. When strange metals are cooled to low temperatures, they too often become superconductors. Most normal metals are not superconductors, at any temperature!
3. The conductivity of strange metals is linked to both Planck’s constant and Boltzmann’s constant, both of which are fundamental constants of nature, suggesting understanding strange metals may lead to deeper insights into the laws of nature.
4. Strange metals are a new state of matter, existing between two known phases of matter, Mott insulators, materials expected to conduct electricity according to electronic band theories but instead act as insulators, typically at low temperatures, and Fermi liquids, similar in properties to a Fermi gas but with differences which are too lengthy to discuss here.
5. Strange metals challenge and push the theories of quantum mechanics to their limit. As the electrical resistance has a linear relationship with temperature, strange metals lose their energy with a rate just within the constraints that the laws of quantum mechanics allow. There exists an unusually slow rate of fluctuations in the electrical charge of Y-Ball.
Why, Oh Y-Ball?
Using Mossbauer spectroscopy, scientists at Rutgers Centre for Materials Theory bombarded Y-ball with gamma rays, in order to measure the rate at which it’s electrical charge fluctuated. In normal metals, electrons hop in and out of the atoms, causing their electrical charge to fluctuate, but at a rate that is thousands of times too fast to be seen by Mossbauer spectroscopy. In the case of Y-Ball, the fluctuations happened in a nanosecond, which is exceedingly slow in the quantum world. The team at Rutgers reasoned that “each time an electron hops into an ytterbium atom, it stays there long enough to attract the surrounding atoms, causing them to move in and out. This synchronized dance of the electrons and atoms slows the whole process so that it can be seen by the Mossbauer.”
The Future of Strange Metals
No one can predict the future, but we may guess with some confidence that quantum materials, such as strange metals, will play a tremendous role in the next generation of technology. These oddities of the metallic family may hold the key to understanding high superconductivity in many materials, aiding researchers to develop more and more efficient methods of energy transfer, reducing the waste of power occurring in transit. Professors working in this field of research believe that decoding the secrets of Y-Ball will give them new ideas and will help humanity design, develop and discover new materials.
As strange metals have similar properties to black holes, they could be the door to unlocking further secrets of the universe, exploring their erratic behaviour may shed light on the base truths of how the physical world works.