Keren

Description

Keren’s generalization of the Abragam relaxation function to a longitudinal field, for fitting the time-dependent muon polarization.

The function is derived in *Phys Rev B, vol. 50, 14, 10039-42 (1994)* and is given by

Pz(t)=Aexp[Γ(t)t]

where the relaxation rate Γ(t) is

Γ(t)t=2Δ2{(ωL2+ν2)νt+(ωL2ν2)(1eνtcos(ωLt))2νωLeνtsin(ωLt)}(ωL2+ν2)2

A=Pz(0) is the polarization at time zero, ν is the fluctuation rate (inverse correlation time), Δ is the distribution width of the local fields and ωL is the Larmor frequency (longitudinal field times muon gyromagnetic ratio).

Properties (fitting parameters)

Name

Default

Description

A

1.0

Polarization at time zero

Delta

0.2

Distribution width of local fields (MHz)

Field

50.0

Longitudinal field (Gauss)

Fluct

0.2

Hopping rate (inverse correlation time, MHz)

Categories: FitFunctions | Muon\MuonSpecific

Source

C++ header: Keren.h

C++ source: Keren.cpp