Irreversible relaxation behaviour of a general class of magnetic systems

Abstract. It is shown that magnetic systems after magnetization in a weak external field for a finite time t mag exhibit a universal time-dependent relaxation behaviour. The normalized magnetization decay after switching off an external field does not depend on any sample parameters and follows a universal law m(t) ∼ log(1 + t mag /t). This universal time dependence is confirmed by magnetic relaxation measurements performed on different powders of small barium hexaferrite magnetic particles at room temperature. The measurements were performed using the PTB SQUID magnetometer in the Berlin Magnetically Shielded Room

Gastrointestinal Transit of a Magnetically Marked Capsule Monitored Using a 37-Channel SQUID-Magnetometer

The gastrointestinal transit of magnetically marked solid pharmaceutical drug dosage forms can be monitored using biomagnetic measurement equipment. The presented study shows that using a 37-channel SQUID-magnetometer the investigation of the gastrointestinal transit of an ingested magnetically marked capsule becomes feasible with a temporal resolution in the order of milliseconds and a spatial resolution in the millimeter range