Adjustable coupling and in-situ variable frequency EPR probe with loop-gap resonators for spectroscopy up to X-band

Abstract

In standard electron paramagnetic resonance (EPR) spectroscopy, the frequency of an experiment is set and the spectrum is acquired using magnetic field as the independent variable. There are cases in which it is desirable instead to fix the field and tune the frequency such as when studying avoided level crossings. We have designed and tested an adjustable frequency and variable coupling EPR probe with loop-gap resonators (LGRs) that works at a temperature down to 1.8 K. The frequency is tuned by adjusting the height of a dielectric piece of sapphire inserted into the gap of an LGR; coupling of the microwave antenna is varied with the height of antenna above the LGR. Both coupling antenna and dielectric are located within the cryogenic sample chamber, but their motion is controlled with external micrometers located outside the cryostat. The frequency of the LGR can be adjusted by more than 1 GHz. To cover a wide range of frequencies, different LGRs can be designed to cover frequencies up to X-band. We demonstrate the operation of our probe by mapping out avoided crossings for the Ni${}_4$ single-molecule magnet to determine the tunnel splittings with high precision.

References in corpus (8)

• Atomic clock transitions in silicon-based spin qubits
• Single-molecule Nanomagnets
• Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy
• Separating hyperfine from spin-orbit interactions in organic semiconductors by multi-octave magnetic resonance using coplanar waveguide microresonators
• A Clock Transition in the Cr${}_7$Mn Molecular Nanomagnet
• Observation of tunneling-assisted highly forbidden single-photon transitions in a Ni${}_4$ single-molecule magnet
• Optimization of Coplanar Waveguide Resonators for ESR Studies on Metals
• Precision ESR Measurements of Transverse Anisotropy in the Single-molecule Magnet Ni${}_4$

Cited by in corpus (4)

• A Gallery of Soft Modes: Theory and Experiment at a Ferromagnetic Quantum Phase Transition
• Characterizing the magnetic noise power spectrum of dark spins in diamond
• Enhancing Coherence with a Clock Transition and Dynamical Decoupling in the Cr${}_7$Mn Molecular Nanomagnet
• Clock Transitions Generated by Defects in Silica Glass