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Magnetic Order Parameter

Description

A Magentic Order Parameter is defined as:

\[y = A_0(1-(\frac{x}{Tc})^{\alpha})^{\beta}\]

where

  • \(A_0\) - the amplitude

  • \(\alpha\) - the balance parameter

  • \(\beta\) - the critical exponent

  • \(Tc\) - the critical temperature

The CriticalTemp (\(Tc\)) needs to be set to the value at which the frequency hits 0. In the figure example below this is around 0.4 and so CritialTemp was set to 0.4 to achieve a fit.

magorder_plot.png

Examples

This has been used for Muon precession frequencies when examining the magentic order in copper pyrazine dinitrate[1].

Properties (fitting parameters)

Name

Default

Description

A0

1.0

amplitude

Alpha

2.0

balance parameter

Beta

0.5

critical exponent

CriticalTemp

1.0

critical temperature

References

[1] Lancaster, T., Blundell, S.J., Brooks, M.L., Baker, P.J., Pratt, F.L., Manson, J.L., Landee, C.P. and Baines, C. (2006) Magnetic order in the quasi-one-dimensional spin-1/2 molecular chain compound in copper pyrazine dinitrate, Phys. Rev. B, Vol 73 Issue 2, 020410 doi: 10.1103/PhysRevB.73.020410.

Categories: FitFunctions | Muon\MuonModelling\Magnetism

Source

C++ header: MagneticOrderParameter.h

C++ source: MagneticOrderParameter.cpp