Magnetization and Superconducting Quantum Interference Device detected Electron Paramagnetic Resonance (SQUID-EPR) of the FIN Trityl Radical
Brant Cage, James H. McNeely, Howard J. Halpern, Stephen E. Russek
The Finland trityl paramagnet is characterized by magnetic susceptibility and a new form of quantitative electron paramagnetic resonance (EPR) that utilizes a superconducting quantum interference device (SQUID) as a detection method. This radical is of interest due to its use as a dynamic nuclear polarization agent as well as a potential magnetic refrigerant and quantum computing bit. The SQUID-EPR data show that the EPR linewidth of a concentrated trityl powder decreases dramatically from 4.4 to 1.4 mT as the temperature is increased from 1.8 to 10 K. The quantitative nature of SQUID-EPR is used to thermodynamically quantify the EPR energy transfer times and saturated fractions. At 95 GHz and 1.8 K, only 40% of the spins are in resonance at the onset of saturation. Conventional dc magnetic susceptibility over 1.8–150 K indicates an S=1/2 Curie-Weiss relationship with little long range interaction. Magnetization versus applied field at 1.8 and 4 K fits a Brillouin function with >80% electronic polarization at a normalized field of gυBυ0H/kTapproximately equal}3. These results provide information required for theoretical modeling and engineering of the trityl radical for a wide range of applications.
, McNeely, J.
, Halpern, H.
and Russek, S.
Magnetization and Superconducting Quantum Interference Device detected Electron Paramagnetic Resonance (SQUID-EPR) of the FIN Trityl Radical, Journal of Applied Physics
(Accessed December 2, 2023)