Advantages of superconducting quantum interference device-detected magnetic resonance over conventional high-frequency electron paramagnetic resonance for characterization of nanomagnetic materials
Brant Cage, Stephen E. Russek, David Zipse, Naresh S. Dalal
A dc-detected high-frequency electron paramagnetic resonance (HF-EPR) technique, based on a standard superconducting quantum interference device (SQUID) magnetometer, has significant advantages over traditional HF-EPR based on microwave absorption measurements. The SQUID-based technique provides quantitative determination of the dc magnetic moment as a function of microwave power, magnetic field and temperature. The EPR spectra obtained do not contain variability in the line shape and splittings that are commonly observed in the standard single-pass transmission mode HF-EPR. We demonstrate the improved performance by comparing EPR spectra for Fe8 molecular nanomagnets using both SQUID-based and conventional microwave-absorption EPR systems.