Magnetic standard reference materials are well-characterized magnetic materials that can be used for calibration of measuring instruments and equipments that allow the determination of magnetic properties of materials. They are also used to evaluate measuring methods and systems. These materials are used in both, research laboratories or control quality laboratories of industry.

In well-known that in a widely used equipment, such as a vibrating sample magnetometer for instance, two main standards are used. A magnetic moment standard is used to calibrate the measuring of this physical quantity while a reference magnetic field is needed to check the calibration of the Hall sensor of the gaussmeter employed to measure the applied magnetic field. Magnetic standard reference materials are developed and provided by specialized laboratories. Each standard is provided to customers with its corresponding certificate. Authorized suppliers offer small spherical and disk shaped Nickel calibration standards as illustrated in Fig. 1. In the following text we describe the main magnetic measurement standards.
		Fig. 1. Usual geometries of the magnetic moment and magnetic susceptibility calibration standards.

Magnetic moment standard. When a sample of any material is placed in a magnetic field of certain intensity a magnetic moment is induced. In experimental methods that do not determine absolutely the magnetic moment of the sample under study, such as SQUID and vibrating sample magnetometers, a standard of known magnetic moment is necessary for calibration of the measuring scale employed. Fig. 2 shows examples of magnetic moment calibration standards certificated by the US National Institute of Standards and Technology (NIST). The Nickel employed for such a purpose has a chemical purity of 99.999 % and its microstructure is equiaxed with a controlled average grain size. The sample is carefully ultrasonically cleaned

Fig. 2a Magnetic moment standard references materials certificated by the US NIST:Nickel sphere	Fig. 2b Magnetic moment standard references materials certificated by the US NIST: Nickel disk

Magnetic susceptibility standard. This standard is made of 99.99 % pure platinum cylindrically shaped which is paramagnetic having a well-known value of the magnetic susceptibility at room temperature (1.27E-08 cubic meter per kilogram at 295 K). This standard is very useful for SQUID magnetometers where an outside source of magnetic flux is undesiderable. It is also useful for calibrating the most sensitive magnetometer range and the true zero field and zero magnetic moment positions in these magnetometers

Magnetic field standard. The magnetic field calibration of the Hall gaussmeters used to measure the magnetizing field applied to the sample under study in any measuring technique must be periodically checked. With such a purpose a cavity having a uniform static magnetic field is used. The Hall sensor is introduced into the cavity in order to check its calibration in the different measuring ranges. Depending of the magnetic field range different ‘calibration magnets’ must be used. Fig. 3 shows a calibration magnet standard designed for transverse Hall probes.
		Fig. 3. Standard magnet used as magnetic field calibration standard.