A sub-Kelvin cryogen-free EPR system

Abstract

We present an EPR instrument built for operation at Q band below 1K. Our cryogen-free Dewar integrates with a commercial electro-magnet and bridge. A description of the cryogenic and RF systems is given, along with the adaptations to the standard EPR experiment for operation at sub-Kelvin temperatures. As a first experiment, the EPR spectra of powdered CrO(OH) [Formula: see text] were measured. The sub-Kelvin EPR spectra agree well with predictions, and the performance of the sub-Kelvin system at 5K is compared to that of a commercial spectrometer.

Hyperfine Structure and Coherent Dynamics of Rare-Earth Spins Explored with Electron-Nuclear Double Resonance at Subkelvin Temperatures

“…In addition, the compatibility of the sub-Kelvin sample temperature with a conventional 3D ENDOR resonator makes this spectrometer a versatile equipment suitable for EPR samples from various research fields. For example, it is also promising to enhance the coherent properties of molecular nanomagnets [46,47]. More intrinsically, the duration of a pulsed EPR experiment should be less than the spin relaxation time, which is typically highly dependent on the sample temperature.…”

A tunable resonator enabled by a soft impedance surface

“…Cavity resonators are radio frequency (RF) components that are used in a wide range of applications, including particle accelerators, 1 dark matter detectors, 2 transducers, 3 and for electron paramagnetic resonance measurements 4 . Usually they are either cylindrical cavities tuned by moving rods to alter the internal field distribution, or smaller reentrant cavities, 5,6 which are tuned by varying the capacitance between a central post and the lid.…”