Understanding a new kind of magnetism
Using low-frequency laser pulses, a team of researchers has carried out the first measurements that reveal the detailed characteristics of a unique kind of magnetism found in a mineral called herbertsmithite.In this material, the magnetic elements constantly fluctuate, leading to an exotic state of fluid magnetism called a “quantum spin liquid.” This is in contrast to conventional magnetism, found in materials called ferromagnets — where all of the magnetic forces align in the same direction, reinforcing each other — or antiferromagnets, where adjacent magnetic elements align in opposite directions, leading to complete cancellation of the material’s overall magnetic field. Although a spin-liquid state has previously been observed in herbertsmithite, there has never been a detailed analysis of how the material’s electrons respond to light — a key to determining which of several competing theories about the material is correct. Now a team at MIT, Boston College and Harvard University has...