mag

Documentation

Overview

package mag provides magnetism-specific constants and the demag kernel.

Index

• Constants
• func CalcDemagKernel(inputSize, pbc [3]int, cellsize [3]float64, accuracy float64) (kernel [3][3]*data.Slice)
• func DemagKernel(inputSize, pbc [3]int, cellsize [3]float64, accuracy float64, cacheDir string) (kernel [3][3]*data.Slice)
• func LoadKernel(fname string) (kernel *data.Slice, err error)
• func MFMKernel(mesh *d.Mesh, lift, tipsize float64) (kernel [3]*d.Slice)
• func SaveKernel(fname string, kernel *data.Slice) error

Constants

const (
	Mu0 = 4 * math.Pi * 1e-7 // Permeability of vacuum in Tm/A
	MuB = 9.2740091523E-24   // Bohr magneton in J/T
	Kb  = 1.380650424E-23    // Boltzmann's constant in J/K
	Qe  = 1.60217646E-19     // Electron charge in C
)

const (
	X = 0
	Y = 1
	Z = 2
)

const SMALL_N = 5

Use 2N-1 padding instead of 2N for sizes up to SMALL_N. 5 seems a good choice since for all n<=5, 2*n-1 only has prime factors 2,3,5,7 (good CUFFT performance). starting from 6 it becomes problematic so we use 2*n.

Functions

func CalcDemagKernel

func CalcDemagKernel(inputSize, pbc [3]int, cellsize [3]float64, accuracy float64) (kernel [3][3]*data.Slice)

Calculates the magnetostatic kernel by brute-force integration of magnetic charges over the faces and averages over cell volumes.

func DemagKernel

func DemagKernel(inputSize, pbc [3]int, cellsize [3]float64, accuracy float64, cacheDir string) (kernel [3][3]*data.Slice)

Obtains the demag kernel either from cacheDir/ or by calculating (and then storing in cacheDir for next time). Empty cacheDir disables caching.

func LoadKernel

func LoadKernel(fname string) (kernel *data.Slice, err error)

func MFMKernel

func MFMKernel(mesh *d.Mesh, lift, tipsize float64) (kernel [3]*d.Slice)

Kernel for the vertical derivative of the force on an MFM tip due to mx, my, mz. This is the 2nd derivative of the energy w.r.t. z.

func SaveKernel

func SaveKernel(fname string, kernel *data.Slice) error