Design and Implementation of Electron Spin Resonance Capability at Low Temperatures to Study Low-Dimensional Quantum Matter

Electron Spin Resonance (ESR) is an experimental technique that gives insight into the unpaired spins of electrons in materials. In low-dimensional spin-1/2 systems, i.e. bulk materials comprising chains of spin or two-dimensional lattices with triangular, square, and honeycomb geometries, spins remain dynamic to very low-temperature as a result of quantum fluctuations, leading to entangled phases of matter called “spin-liquids”. Probing these low-temperature states is important because their elementary excitations are fractional: these “spinons” can propagate independently as pairs over nanometer length scales. ESR, through the line shape of the microwave absorption, is sensitive to the existence and dynamics of spinons.

Included in this talk is a focus on creating loop gap resonators, resonance structures which enable the selection of microwaves for absorption by the sample in an ESR device. LGRs are unique in that their designs are adjustable to many different sample sizes and frequency ranges, decreasing sample restraints compared to cavity resonators. Through the design, creation, and testing of these LGRs, we were able to confirm their viability for future use in the project.