Vinamax

First example: Precession and Damping

In this example a single particle is created without anisotropy. It starts off with a magnetisation along the x-direction and an external field along the z-direction is applied. The magnetisation should gyrate around this axis with a frequency of 28 GHz/T and damp slowly towards the z-direction, as dictated by the Landau-Lifshitz equation.

package main

import (
. "github.com/JLeliaert/vinamax"
)

func main() {

//Defines the world at location 0,0,0 and with a side of 1e-8 m
World(0,0,0,1e-8)
//Adds a single particle in the origin
Addsingleparticle(0,0,0)

//the particle has radius 10 nm
Particle_radius(10.e-9)

//apply an external field along the z direction of 10mT
//B_ext can be an arbitrary function of time
B_ext = func(t float64) (float64, float64, float64) { return 0, 0, 0.1 }
//Don't calculate the demagnetizing field
Demag=false
//Don't use the dipole approximation method
FMM=false

//sets the saturation magnetisaton of the particles at 860e3 A/m
Msat(860e3)	

//timestep : 1fs
Dt = 1e-15
//initialise time at zero
T = 0.
//temperature=0
Temp = 0.
//Gilbert damping constant=0.02
Alpha = 0.02
//anisotropy constant=0
Ku1 = 0

//anisotropy axis along the y-direction
Anisotropy_axis(0, 1, 0)

//initialise the magnetisation along the x direction
M_uniform(1,0,0)

//write output every 5e-12s
Output(5e-12)

//run for 5 ns
Run(5.e-9)
}

The results of the simulation are visualised below and to validate the code, the comparison with Mumax3 of (@barnex) has been made.