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CriticalPeakRelaxationRate

Description

The Critical Peak Relexation Rate is defined as:

\[y = \frac{B_1}{(|x - T_c|)^a} + B_1\Theta(x < T_c) + B_2\Theta(x >= T_c)\]

where: - \(S_c\) - Scaling - \(T_c\) - Critical temperature - \(a\) - Critical exponent - \(B_1\) - is a non-critical background when \(x < T_c\) - \(B_2\) - is a non-critical background when \(x >= T_c\)

When fitting users should set \(T_c\) as the temperature at which the peak occurs. Users are also asked to supply two values for \(B_g\). The first should be the value of y when x is at it’s minimum. The second should be the value of y when x is at its maximum, minus the first background value.

Examples

An example of when this might be used is for examining the Chiral-like critical behaviour in antiferromagnet Cobalt Glycerolate[1] or in muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets[2].

Attributes (non-fitting parameters)

Name

Type

Default

Description

Delta

Properties (fitting parameters)

Name

Default

Description

Scaling

1.0

coefficient for scaling

CriticalTemp

0.01

coefficient for critical temperature

Exponent

1.0

coefficient for critical exponent

Background1

0.0

coefficient for non-critical background when x < Critical Temperature

Background2

0.0

coefficient for non-critical background when x > Critical Temperature

References

[1] Pratt, F.L, Baker, P.J., Blundell, S.J., Lancaster, T., Green, M.A., and Kurmoo, M. (2007). Chiral-Like Critical Behaviour in the Antiferromagnet Cobalt Glycerolate. Phys. Rev. Lett., Vol 99 Issue 1, 017202 doi: 10.1103/PhysRevLett.99.017202. [2] Pratt, F. et al (2009) Muon spin relaxation studies of critical fluctuations and diffusive spin dynamics in molecular magnets. Physica B: Condensed Matter, Volume 404 Issues 5–7, pp585-589 doi: 10.1016/j.physb.2008.11.123.

Categories: FitFunctions | Muon\MuonModelling\Magnetism

Source

C++ header: CriticalPeakRelaxationRate.h

C++ source: CriticalPeakRelaxationRate.cpp