I’m always super excited when science makes a breakthrough. The last major one was the Higg’s Boson. This time it’s the existence of Quantum Spin Liquids (QSL), which has been theorised since 1987 but never discovered. This is reminiscent of the Higg’s Boson, which was predicted by the Standard Model but not found until recently, hence my excitement. It’s just very satisfying to see even more “gaps” filled in by science.
So, what is QSL? I have some knowledge of the quantum mechanics field but I can only really give you guys a basic overview of this discovery. QSL confirms the discovery of a third fundamental state of magnetism. Originally, magnetism was described in two states:
This type of magnetism has been known and used for centuries. It is the force behind a compass’s needle and your typical bar magnet. A ferromagnet’s spin (charge) of every electron is aligned in the same direction, causing two distinct poles.
The electrons in these have an opposite spin to their neighbouring electrons, leading to a net effect of zero magnetism. Generally, these exist only at certain low temperatures and are used in giant magnetoresistors. You might be wondering what the point of having zero net magnetism is – well think of it as a control or a switch. Sometimes you want the magnet to switch off.
The existence of QSL posits a new, third type of magnetism that is described as liquid in that the magnetic orientations of the electrons fluctuate, and thus the object’s magnetic state is constantly in flux. Most magnetic solids trend towards a stable magnetic state at low temperatures, but in a QSL, the electron spin will remain in flux even at temperatures close to absolute zero.
Massachusetts Institute of Technology (MIT) just published (literally just then – like today) news of their discovery of QSL in a mineral known as Herbertsmithite. The crystalline structure of this mineral is called a kagome lattice, a weaving pattern of overlaid triangles forming a hexagon at its centre. Here’s a picture to clarify what I’m saying: (the arrows represent electron spin direction)
To get a bit more technical, the reason why the kagome lattice is so important to QSL is because of the triangle. It has three points with a copper atom at each. The electrons on two of the corners can align but the third one cannot align with both, thus causing magnetic frustration (fluctuating magnetism).
Because a combination of ferromagnets and antiferromagnets are used to create hard drives, the main proposed usage of this discovery is in the field of information processing.
However, the existence of frustrated magnetism has been proposed to lead to other interesting phenomena such as magnetic monopoles, which would support M-Theory, among other things.
All in all though, the most exciting thing is the discovery of something fundamentally new. Adding on top of what we already know is great but when you discover a new fundamental state, it points to an even greater science that we’ve never seen before – something to perhaps replace the Standard Model, as they are trying to do at CERN, or perhaps conclude the theory of everything, as M-Theory and Quantum Loop Gravity are trying to do.