Robert Krumland-Dunning

Major: Physics
Mentors: Antonin Sojka, Professor Mark Sherwin

Two-Axis Rotating Sample Holder For Electron Paramagnetic Resonance Spectroscopy

Electron paramagnetic resonance spectroscopy (EPR) is a powerful tool used for studying materials with unpaired electrons through the excitation of their spin states in the presence of an external magnetic field. These excitations can be anisotropic with respect to the external field and thus changing the sample’s orientation gives deeper insight into its structure. However, there is no general solution for sample rotation inside an external magnetic field and thus solutions are custom built for the specific requirements of the exact spectrometers. Our project presents the development of a rotating sample holder for use with a broad-range EPR spectrometer powered by a Free Electron Laser. The novelty of this sample holder is its ability to switch the axis of rotation from parallel to perpendicular with respect to the magnetic field. Moreover, the sample holder works in EPR systems operating at magnetic fields up to 16 T, frequencies from 140 to 500 GHz, and temperatures ranging from 1.8 to 300 K. Due to these constraints, the body is constructed from Poly Ether Ether Ketone (PEEK), a highly machinable and temperature stable polymer, and a piezoelectric rotator with sub-degree precision is employed(ANR51/RES/LT, Attocube Systems). Magnetic field modulation coils, a temperature sensor, and heaters are also required. Our rotating sample holder will expand the usage possibilities for high field spectroscopy at Santa Barbara by enabling orientation dependent research with EPR.