Dynamic transverse susceptibility in Au-Fe-Au "nano-onions"

A precision radio-frequency (RF) transverse modulation technique based on a resonant tunnel diode oscillator (TDO) has been used to study the dynamic susceptibility in novel ring-shaped single domain Fe nanoparticles synthesized using reverse-micelle chemistry. Hysteresis loops measured using a SQUID magnetometer indicate a large coercivity (Hc = 400Oe) below the blocking temperature (TB ~52K). The dynamic susceptibility shows remarkable consistency with the M-H data and exhibits peaks at characteristic anisotropy fields. Overall, these RF experiments are well suited to probe the magnetic anisotropy in nanophase materials.