John Colton's blog

I was out of town most of last week, going to the American Physical Society's March Meeting in Denver. I presented a talk--here's my abstract:

In order to do spin echo measurements of the T2 spin coherence time in GaAs and related materials, one must have a resonant microwave cavity; the resonance serves mainly to increase the strength of the magnetic field at the sample. In order to probe materials with g-factors as low as |g| = 0.1 (such as quantum-confined GaAs samples, and bulk/quantum-confined AlGaAs alloys) in moderate magnetic fields (< 7 T), we have selected a resonant frequency of around 10 GHz for the resonator design. In order to fit a 10 GHz cavity into moderately-sized (< 1 inch) magnet bore, however, a high dielectric material must be used, a so-called “dielectric resonator”. We will present the design and testing of such a resonant cavity (resonant mode: TE011), that additionally allows for optical access of the sample, as well as a highly-variable resonant frequency.