Adapted from this Advanced Light Source news article
Typically, electrons move through an electronic device like marbles rolling down a hill. A team of researchers was curious if it might be possible to alter a material ever so slightly to initiate the exotic quantum states locked within electrons. The results of their study are available in the June issue of the journal Nature Communications.
“In our work, we discovered that, in ultra-thin materials, electrons confined to one-dimensional channels can split into separate waves of charge and spin, moving independently of each other,” said Antonio Rossi, a researcher at the Italian Institute of Technology and co-first author on the study. “It’s as if a marble rolled down a wire and suddenly turned into two ripples traveling at different speeds, one electric and one magnetic.”
The researchers engineered a thin film composed of a tungsten disulfide (WS2) matrix where one tungsten atom is sandwiched between two sulfur atoms. The WS2 film is grown on top of a single layer of carbon atoms (graphene), which sits on a silicon carbide wafer. The research team bombarded the three-atom-high construction with argon gas to insert one-dimensional defects in the thin film. These defects offered a pathway to explore a whole new world of electron behavior.
The team performed measurements at the Molecular Foundry at Berkeley Lab using ultra-stable scanning tunneling microscopy and spectroscopy, a technique that illustrates the distribution of electrons on the surface at the atomic level within individual defects.
They paired this analysis with quantum materials growth and electronic structure measurements at Beamline 7.0.2 (MAESTRO) at the ALS at Berkeley Lab, which uses a high-flux, tunable photon source and high resolution electron energy analyzer to directly measure how electrons move through the material and how their energies are arranged. This cross-correlative endeavor provides atomic to nanoscopic level information about the origin of Tomonaga–Luttinger liquid (TLL) behavior.
Defying conventional behavior, electrons in TLLs form new collective entities, called quasiparticles. TLLs allow for the separation of an electron’s charge and spin, which travel independently and in fractional amounts. As a result, materials that are normally insulators can suddenly become superconductors or exhibit entirely new types of behavior. In addition, TLLs can propagate charge 10 to 100 times faster compared to conventional electronics, opening a unique solution to low-power electronics.
