Magnetisation remanent

Figure 2 shows the two hysteresis loops for a medium and a head material. The coercivity, the saturation magnetisation, Af or iaduction, B, remanent magnetisation, M or iaduction, B, and the permeabiHty, p, differ for the two materials. 

If a very high field is appHed the magnetisation can reach its saturated state ia which all the magnetic dipoles are aligned ia the direction of the field. If the magnetic field is switched off, the remanent magnetisation M is left. If the M (or B) is then reduced to sero, a special field strength, the coercivity, is required. 

Substances used as permanent magnets need a large coercive force, so that they are not easily demagnetised and preferably should also have a large remanent magnetisation. These substances have fat hysteresis curves. They are often made from... 

We discuss in this section whether routes may be envisaged towards nanocomposite materials with magnetic properties significantly superior to present properties. The target remanent magnetisation value is estimated to be jUtMr = 1.2 T in isotropic systems and poMt = 1.5 T in anisotropic... 

Screen-printing, bonding and injection moulding are well adapted to the fabrication of thick films for MEMS. Most often, isotropic ribbons are used, and the dilution of the powders in the non magnetic binder limits further the value of the remanent magnetisation. 

Most of the samples from Bone Chamber (Fig. 7) show simple demagnetisation paths dominated by one component with a direction broadly similar to the present-day field at Buchan (declination = 13°, inclination = -68°, based on the International Geomagnetic Reference Field for epoch 1995.0), after removal of soft post-sampling components by 4 mT demagnetisation. Remanence has very low coercivity, with mean destructive fields of <10 mT, and remanence remaining after 30 mT demagnetisation is less than 5% of natural remanent magnetisation (NRM). NRM varies between 172 mAm (sample BC4) and 330 mAm (sample BC2). 

In the magnetic remanence experiments the samples are exposed to a combination of much stronger specific magnetic fields than those that are applied in magnetic susceptibility analyses. After exposnre to each successive magnetic field, the remanent magnetisation is measured. When the magnetisation is measnred out of the field , only substances that are... 

The magnetic remanence indnced in a sample in the way described above is known as the Isothermal Remanent Magnetisation (IRM). A particular field that has been used can be denoted IRMjomT J 4oomT> etc. for specific forward fields andIRM 20mT ... 

APPLICATION OF MINERAL MAGNETIC TECHNIQUES Gyro rotational remanent magnetisations (GRM/RRM)... 

Potter, D. K. A. Stephenson. 1986. The detection of line particles of magnetite using anhysteretic and rotational remanent magnetisations. Geophys. J. R. AstroiL Soc. 87 569-582. 

Out-of-field magnetisation The magnetisation of a sample measured when the sample has been removed from the magnetic field (i.e., having a remanent magnetisation). 

The remanence or remanent magnetisation (M ), which is the retained magnetisation at zero field from the saturation state. 

Fig. 2 Saturation hysteresis loop (black line) and minor loop (red line), with indication of the most representative parameters saturation magnetisation (M,), remanent magnetisation (At,) and coercive field...

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