FERROMAGNETIC-RESONANCE OF MICROMETER-SIZED SAMPLES

Submicrometer-sized slotline and coplanar waveguide devices were used for ferromagnetic resonance (FMR) measurement on submicrometer-sized m agnetic fine particles. FMR measurements were taken on individual magn etic disks, having diameters ranging from 50 to 1 mu m, using either a slotline-coplanar waveguide (CPW) junction device or a coplanar waveg uide transmission line junction device. The magnetic samples were etch ed from a 105 nm thick amorphous Fe80B15Si5 film on a quartz substrate . Absorption modes, which were measured with the submicrometer-sized s lotline CPW, followed the Kittel magnetic resonance model for frequenc ies from 1 to 20 GHz for the 1 mu m diam disk. By detecting the second harmonic of the lock-in amplifier's reference signal, we have measure d disk samples as small as 1 mu m in diameter. We estimated that the s ensitivity is of the order of 3 x 10(9) spins, almost four orders of m agnitude better than the sensitivity of a standard electron paramagnet ic resonance system. (C) 1997 American Institute of Physics.