Abstract: An intermetallic or iron aluminide magnetically readable medium and a method of forming and reading the same are provided herein. Also provided is an identification card or tag, a key, an anti-counterfeiting measure, an anti-forging measure. The intermetallic or iron aluminide magnetically readable medium includes a magnetically readable surface, wherein the magnetically readable surface contains one or more first magnetically readable regions of the intermetallic or iron aluminide surrounded by one or more second magnetically readable regions. Additionally, the intermetallic or iron aluminide magnetically readable medium can be coated, encapsulated or concealed within a material.

Abstract: A local magnetic susceptibility unit is adapted to measure the AC magnetic susceptibility of a surface region of a sample. The unit comprises a sensing element and one or more balancing elements arranged in a circuit. When a sample is placed proximate to the sensing element the sample induces an imbalance voltage in the circuit.

Abstract: A method is provided for producing a doped dilute ferromagnetic semiconductor material, by doping Zinc Oxide in bulk form with manganese to a maximum level of 5 atomic percent concentration. The material is preferably sintered at a maximum temperature of 650° C. The result of this process is a semiconductor material comprising Mn-doped ZnO with a Mn concentration not exceeding 5 atomic percent, wherein the Mn-doped ZnO is ferromagnetic within at least a part of the temperature range from about 218 Kelvin to about 425 Kelvin.