Regular readers of Physics World know that we have a penchant for materials and nanotechnology research. I developed my fondness for materials physics when I did a PhD many years ago on the magnetic properties of ultrathin films and my interest has never waned. So here are five of my favourite materials and nanotechnology stories of 2020.
Bioinspiration and biomimicry involve studying how living organisms do something and using that insight to develop new technologies. Pit vipers have two special organs on their heads called loreal pits that allow them to “see” the infrared radiation given off by their warm-blooded prey. Now, Pradeep Sharma and colleagues have worked out that the snakes use cells that act as a soft pyroelectric material to convert infrared radiation into electrical signals that can be processed by their nervous systems. As well as potentially solving a longstanding puzzle in snake biology, the work could also aid the development of thermoelectric transducers based on soft, flexible structures rather than stiff crystals.
Is there anything that perovskites cannot do? This family of crystalline materials is usually associated with high-performance solar cells, but perovskites are true wonder materials that are finding increasingly exotic applications. Now, researchers have shown that certain perovskites could be ideal platforms for creating Bose–Einstein condensates (BECs) of excitons. Excitons are quasiparticles that comprise an electron–hole pair (and we do love a quasiparticle at Physics World). BECs are normally made from atomic gases that must be chilled to near absolute zero. However, Kai Chang and colleagues reckon that exciton BECs in perovskites could exist at a balmy 77 K.
There is no shortage of clever applications for graphene – a sheet of carbon just one atom thick – but research really fired my imagination this year. The rippling thermal motion of a tiny piece of graphene has been harnessed by a special circuit that delivers low-voltage electrical energy. The system was created by Paul Thibado and colleagues, who say that if it could be duplicated enough times on a chip, it could deliver “clean, limitless, low-voltage power for small devices”.
Physics World announces its Breakthrough of the Year finalists for 2020
The topological properties of matter have been a very hot topic over the past few years, so it is no surprise that in 2020 physicists have observed “topological superconductivity” for the first time. Nai Phuan Ong and colleagues have measured a robust supercurrent at the edge of a superconductor that is very different to the supercurrent in the material’s bulk. The team does not yet fully understand the reason for why the edge supercurrent remains independent of bulk supercurrent, but they believe it could come from the topologically protected edge states in the material.
Polymer strands are often described as worm-like, so why not use living worms to gain insights into polymer materials? And if you want to alter the behaviour of the worms, there is no better way than to give them a stiff drink. That is exactly what Antoine Deblais and colleagues did – using worms to gain new insights into the properties of poorly understood “active polymer” materials by measuring the viscosity of clusters of sludge worms as they were subjected to shear forces. The wriggling activity of the worms was controlled by adjusting their temperature, and the creatures were temporarily knocked out using alcohol.