Magnetisation curve

The observation that XmT of (bpym, Se) is temperature-independent between 50 and 110 K and that no maximum in the susceptibility occurs at temperatures below 50 K suggests that no intramolecular antiferromagnetic coupling in pairs remains in this temperature regime. In fact the magnetisation curves [9] of (bpym, S) and (bpym, Se) at 1.9 K clearly indicate the different nature of the spin pairs involved in each compound in the ground state (Fig. 8). 

This method is based on the Villari effect applying a uniaxial stress to a ferromagnetic substance induces a magnetoelastic anisotropy which may modify all the parameters of its magnetisation curve, e.g. magnetic susceptibility, coercive force, and so on. Some experimental techniques to measure the strain-induced anisotropy are discussed shortly below. 

Fig. 6 Variable field isothermal magnetisation curves, recorded at different temperatures, for complex [Mn907(thme)(02CMe)n(py)3(H20)2] (16), emphasising large hysteresis loops caused by slow relaxation of the magnetisation and clearly showing steps as a result of enhanced relaxation due to quantum timnelling...

From Fig. 8.13 it can be seen that the resolution of the steps on the magnetisation curve depends upon the balance between T, B and D. For fixed T and low D no resolution is observed. With increasing D the steps become clearly visible at higher fields. 

Fig. 4.10, instead of in the form of latent heat at the transition. This results in a magnetisation curve with small variations at low temperatures and a large decrease as T approaches Tq, Fig. 4.11. The concepts of reduced magnetisation and reduced temperature, m = M(T)fM(0), and t = T/Tq, respectively, are used to compare materials with different spontaneous magnetisations and Curie points. M T) represents the magnetisation value at temperature T, and M(0) the value at 0 K. Since in ferromagnets magnetisation is always maximum for 0 K, a decreasing curve is obtained.

Fig. 4.33. Magnetisation curve of a Vitrovac amorphous alloy at room temperature.

Fig. 4.34. Schematic magnetisation curve showing the important parameters initial permeability, Hi (the slope of the curve at low fields), the critical field. He and the main magnetisation mechanism in each magnetisation range.

Fig. 4.36. Effects of compressive and tensile stress on the magnetisation curve of Ni. (Adapted from Cullity, 1972.)...

Fig. 4.41. Magnetisation curve OAB, and hysteresis loop BCDEB as combinations of domain wall bowing, unpinning and displacement (Globus, 1977).

A good fitting can lead to an estimate of the magnetic moment per molecule, as well as evidence of a ferro-, or an antiferromagnetic arrangement. The reason is that, since the transition temperature can be as low as a few kelvins, it may be extremely difficult to observe clear evidence of a magnetisation curve, or a magnetisation vs T curve. 

Fig. 6.43. A typical magnetisation curve showing, in the inset, the Barkhausen effect.

Fig. 9. Relative magnetisation curves for an array of magnetic ions with random easy axis anisotropy at T = 0 K.

Tensile strength, plasticity, dielectric stren h, magnetisation curve of ferromagnetic substances... 

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