MIT experiment realizes ‘Quantum Spin Liquid’
A team at the Massachusetts Institute of Technology has discovered the first evidence of the Quantum Spin Liquid magnetic state within Herbertsmithite minerals.
This month, MIT realized for the first time a new type of magnetism. Originally theorized by physicist Phil Anderson in 1973, MIT is the first to show evidence of a Quantum Spin Liquid (QSL) in crystalline herbertsmithite in an experiment by Professor Young Lee and his team at the Massachusetts Institute of Technology.
A chunk of Herbertsmithite
The experiment began with the team spending years to grow small samples of very pure herbertsmithite crystals. They then used the process of neutron scattering to observe the signs of spin liquid physics. Using the Multi-Axis Crystal Spectrometer (MACS) at the NIST Center for Neutron Research, the team fired beams of neutrons at the samples and measured the energies from the scattered neutrons. Strong evidence for the discovery of the spin liquid came into focus after the energies recorded varied widely, unlike the uniform energies of most magnetic materials.
This representation of neutron scattering shows the magnetic effects within Herbertsmithite crystals. The green regions depict a higher scattering of neutrons from the disorder. A highly-ordered magnetic material shows only small spots of green, while a highly-disordered material tends to be uniform in color. The amount of both colors shows the order and disorder unique to spin liquids.
QSL is a third type of magnetism after ferromagnetism and antiferromagnetism and is considered a “liquid” due to its disordered state, like water is to crystalline ice, despite being a solid crystal. The atoms in herbertsmithite form a kagome lattice, a repeating triangle pattern. The copper atoms within the mineral form at the points of the triangles in the lattice and interact with each other in a typical up-down spin like in ferromagnetism. However, the electron spin at the third corner cannot align with the two other corners and continuously flips its spin.
What makes Quantum Spin Liquid so unique is its ability to maintain this disorder even at very low temperatures. While this is the start to some very fundamental research, it will take quite some time for QSLs to have any practical application. Still, we may see them utilized in data storage and quantum computing in the future.
For more information, visit the source: NIST