Core

AxialDriver

Axial driver class.

CVector

CVector class. Represents a 3D vector.

__init__(x, y, z)

Initialises a 3D vector.

Parameters:

Name	Type	Description	Default
x	float	x component of the vector	required
y	float	y component of the vector	required
z	float	z component of the vector	required

length()

Returns the length of the vector.

normalize()

Normalizes the vector.

tolist()

Converts the vector to a list.

Junction

clearLog()

Reset current simulation state.

getLayerMagnetisation(layerId)

Get the magnetisation of a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required

getLog()

Retrieve the simulation log [data].

runSimulation(totalTime, timeStep=Ellipsis, writeFrequency=Ellipsis, persist=Ellipsis, log=Ellipsis, calculateEnergies=Ellipsis)

Main run simulation function. Use it to run the simulation.

Parameters:

Name	Type	Description	Default
totalTime	float	total time of a simulation, give it in seconds. Typical length is in ~couple ns.	required
timeStep	float	the integration step of the RK45 method. Default is 1e-13	Ellipsis
writeFrequency	float	how often is the log saved to? Must be no smaller than timeStep. Default is 1e-11.	Ellipsis
persist	bool	whether to save to the filename specified in the Junction constructor. Default is true	Ellipsis
log	bool	if you want some verbosity like timing the simulation. Default is false	Ellipsis
calculateEnergies	bool	[WORK IN PROGRESS] log energy values to the log. Default is false.	Ellipsis

setIECDriver(bottomLayer, topLayer, driver)

Set IEC interaction between two layers. The names of the params are only for convention. The IEC will be set between bottomLyaer or topLayer, order is irrelevant.

Parameters:

Name	Type	Description	Default
bottomLayer	str	the first layer id	required
topLayer	str	the second layer id	required

setLayerAnisotropyDriver(layerId, driver)

Set anisotropy driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the id of the layer.	required
driver	ScalarDriver	the anisotropy driver to be set.	required

setLayerCurrentDriver(layerId, driver)

Set a current driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required
driver	ScalarDriver	the driver	required

setLayerDampingLikeTorqueDriver(layerId, driver)

Set the damping like torque driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required
driver	ScalarDriver	the driver	required

setLayerExternalFieldDriver(layerId, driver)

Set an external field driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the id of the layer.	required
driver	AxialDriver	the field driver to be set.	required

setLayerFieldLikeTorqueDriver(layerId, driver)

Set the field like torque driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required
driver	ScalarDriver	the driver	required

setLayerMagnetisation(layerId, mag)

Set the magnetisation of a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required
mag	CVector	the magnetisation	required

setLayerOneFNoise(layerId, sources, bias, scale)

Set 1/f noise for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the layer id	required
sources	int	the number of generation sources (the more the slower, but more acc.)	required
bias	float	the bias of the noise (p in the Multinomial distribution)	required
scale	float	the scale of the noise, additional scaling factor	required

setLayerTemperatureDriver(layerId, driver)

Set a temperature driver for a layer.

Parameters:

Name	Type	Description	Default
layerId	str	the id of the layer.	required
driver	ScalarDriver	the temperature driver to be set.	required

setQuadIECDriver(bottomLayer, topLayer, driver)

Set secondary (biquadratic term) IEC interaction between two layers. The names of the params are only for convention. The IEC will be set between bottomLyaer or topLayer, order is irrelevant.

Parameters:

Name	Type	Description	Default
bottomLayer	str	the first layer id	required
topLayer	str	the second layer id	required

Layer

__init__(id, mag, anis, Ms, thickness, cellSurface, demagTensor, temperature=Ellipsis, damping=Ellipsis)

The basic structure is a magnetic layer. Its parameters are defined by the constructor and may be altered by the drivers during the simulation time. If you want STT, remember to set the reference vector for the polarisation of the layer. Use setReferenceLayer function to do that.

Parameters:

Name	Type	Description	Default
id	str	identifiable name for a layer -- e.g. "bottom" or "free".	required
mag	CVector	initial magnetisation. Must be normalised (norm of 1). Used for quicker convergence.	required
anis	CVector	anisotropy of the layer. A normalised vector	required
Ms	float	magnetisation saturation. Unit: Tesla [T].	required
thickness	float	thickness of the layer. Unit: meter [m].	required
cellSurface	float	surface of the layer, for volume calculation. Unit: meter^2 [m^2].	required
damping	float	often marked as alpha in the LLG equation. Damping of the layer. Default 0.011. Dimensionless	Ellipsis

createSOTLayer(id, mag, anis, Ms, thickness, cellSurface, demagTensor, damping=0.11, fieldLikeTorque=0, dampingLikeTorque=0) staticmethod

Create SOT layer -- including damping and field-like torques that are calculated based on the effective Spin Hall angles.

Parameters:

Name	Type	Description	Default
id	str	identifiable name for a layer -- e.g. "bottom" or "free".	required
mag	CVector	initial magnetisation. Must be normalised (norm of 1). Used for quicker convergence.	required
anis	CVector	anisotropy of the layer. A normalised vector	required
Ms	float	magnetisation saturation. Unit: Tesla [T].	required
thickness	float	thickness of the layer. Unit: meter [m].	required
cellSurface	float	surface of the layer, for volume calculation. Unit: meter^2 [m^2].	required
damping	float	often marked as alpha in the LLG equation. Damping of the layer. Default 0.011. Dimensionless.	0.11

createSTTLayer(id, mag, anis, Ms, thickness, cellSurface, demagTensor, damping=0.011, SlonczewskiSpacerLayerParameter=1.0, beta=0.0, spinPolarisation=0.0) staticmethod

Create STT layer -- with the standard Slomczewski formulation.

Parameters:

Name	Type	Description	Default
id	str	identifiable name for a layer -- e.g. "bottom" or "free".	required
mag	CVector	initial magnetisation. Must be normalised (norm of 1). Used for quicker convergence.	required
anis	CVector	anisotropy of the layer. A normalised vector	required
Ms	float	magnetisation saturation. Unit: Tesla [T].	required
thickness	float	thickness of the layer. Unit: meter [m].	required
cellSurface	float	surface of the layer, for volume calculation. Unit: meter^2 [m^2].	required
damping	float	often marked as alpha in the LLG equation. Damping of the layer. Default 0.011. Dimensionless.	0.011
SlonczewskiSpacerLayerParameter	float	Slomczewski parameter. Often marked as lambda.	1.0
beta	float	beta parameter that scales FL/DL ratio.	0.0
spinPolarisation	float	the spin effectiveness.	0.0

getId()

Get Id of the layer

setAlternativeSTT(setAlternative)

Switch to an alternative STT forumulation (Taniguchi et al.) https://iopscience.iop.org/article/10.7567/APEX.11.013005

Parameters:

Name	Type	Description	Default
setAlternative	bool	whether to set the alternative STT formulation	required

setAnisotropyDriver(driver)

Set anisotropy driver for the layer. It's scalar. The axis is determined in the layer constructor

setBottomDipoleTensor(tensor)

Set a dipole tensor from the bottom layer.

Parameters:

Name	Type	Description	Default
tensor	List[CVector]	the dipole tensor to be set.	required

setDampingLikeTorqueDriver(driver)

Set a driver for the damping like torque of the layer.

Parameters:

Name	Type	Description	Default
driver	ScalarDriver	the driver to be set.	required

setFieldLikeTorqueDriver(driver)

Set a driver for the field like torque of the layer.

Parameters:

Name	Type	Description	Default
driver	ScalarDriver	the driver to be set.	required

setKappa(kappa)

Set the kappa parameter for the layer -- determines SOT mixing Hdl * kappa + Hfl Allows you to turn off Hdl. Turning Hfl is via beta parameter.

Parameters:

Name	Type	Description	Default
kappa	float	the kappa parameter	required

setMagnetisation(mag)

Set the magnetisation of the layer.

Parameters:

Name	Type	Description	Default
mag	CVector	the magnetisation to be set.	required

setOerstedFieldDriver(driver)

Set an Oersted field driver for the layer.

Parameters:

Name	Type	Description	Default
driver	AxialDriver	the field driver to be set.	required

setReferenceLayer(ref)

Set a reference layer for the STT.

Parameters:

Name	Type	Description	Default
ref	CVector	the reference layer vector.	required

setTemperatureDriver(driver)

Set a driver for the temperature of the layer. Automatically changes the solver to Euler-Heun.

setTopDipoleTensor(tensor)

Set a dipole tensor from the top layer.

Parameters:

Name	Type	Description	Default
tensor	List[CVector]	the dipole tensor to be set.	required

NullDriver

Bases: ScalarDriver

__init__()

An empty driver that does nothing. Use in Axial Driver when the axis is to be id.

Reference

Reference layer indicator.

ScalarDriver

getConstantDriver(constantValue) staticmethod

Constant driver produces a constant signal of a fixed amplitude.

Parameters:

Name	Type	Description	Default
constantValue	float	constant value of the driver (constant offset/amplitude)	required

getCurrentScalarValue(time)

Parameters:

Name	Type	Description	Default
time	float	time in seconds	required

Returns:

Type	Description
float	the scalar value of the driver at time.

getGaussianImpulseDriver(constantValue, amplitude, t0, sigma) staticmethod

Gaussian impulse driver. It has amplitude starts at t0 and falls off with sigma.

Formula: A * exp(-((t - t0) 2) / (2 * sigma 2))

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
t0	float	start of the pulse	required
sigma	float	fall-off of the Gaussian pulse	required

getGaussianStepDriver(constantValue, amplitude, t0, sigma) staticmethod

Gaussian step driver (erf function). It has amplitude starts at t0 and falls off with sigma.

Formula: f(t) = constantValue + amplitude * (1 + erf((t - t0) / (sigma * sqrt(2))))

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
t0	float	start of the pulse	required
sigma	float	fall-off of the Gaussian pulse	required

getPosSineDriver(constantValue, amplitude, frequency, phase) staticmethod

Produces a positive sinusoidal signal with some offset (constantValue), amplitude frequency and phase offset.

Parameters:

Name	Type	Description	Default
constantValue	float	vertical offset. The sine will oscillate around this value.	required
amplitude	float	amplitude of the sine wave	required
frequency	float	frequency of the sine	required
phase	float	phase of the sine in radians.	required

getPulseDriver(constantValue, amplitude, period, cycle) staticmethod

Produces a square pulse of certain period and cycle

Parameters:

Name	Type	Description	Default
constantValue	float	offset (vertical) of the pulse. The pulse amplitude will be added to this.	required
amplitude	float	amplitude of the pulse signal	required
period	float	period of the signal in seconds	required
cycle	float	duty cycle of the signal -- a fraction between [0 and 1].	required

getSineDriver(constantValue, amplitude, frequency, phase) staticmethod

Produces a sinusoidal signal with some offset (constantValue), amplitude frequency and phase offset.

Parameters:

Name	Type	Description	Default
constantValue	float	vertical offset. The sine will oscillate around this value.	required
amplitude	ScalarDriver	amplitude of the sine wave	required
frequency	float	frequency of the sine	required
phase	float	phase of the sine in radians.	required

getStepDriver(constantValue, amplitude, timeStart, timeStop) staticmethod

Get a step driver. It has amplitude between timeStart and timeStop and 0 elsewhere

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
timeStart	float	start of the pulse	required
timeStop	float	when the pulse ends	required

getTrapezoidDriver(constantValue, amplitude, timeStart, edgeTime, steadyTime) staticmethod

Create Trapezoid driver. Has a rising and a falling edge.

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
timeStart		start of the pulse	required
edgeTime	float	time it takes to reach the maximum amplitude	required
steadyTime	float	time it spends in a steady state	required

SolverMode

SolverMode Indicator

c_dot(arg0, arg1)

Compute dot (scalar) product of two CVectors.

constantDriver(constant)

Constant driver produces a constant signal of a fixed amplitude.

Parameters:

Name	Type	Description	Default
constant	float	constant value of the driver (constant offset/amplitude)	required

gaussianImpulseDriver(constantValue, amplitude, t0, sigma)

Gaussian impulse driver. It starts with an max amplitude at t0 and falls off with sigma.

Formula:

\(A * \exp(-(t - t_0)^2 / (2\sigma^2))\)

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
t0	float	start of the pulse	required
sigma	float	fall-off of the Gaussian pulse	required

gaussianStepDriver(constantValue, amplitude, t0, sigma)

Gaussian step driver (erf function). It starts at t0 and falls off with sigma.

Formula:

\(f(t) = c + A + A\mathrm{erf}((t - t_0) / (\sigma \sqrt(2)))\)

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
t0	float	start of the pulse	required
sigma	float	fall-off of the Gaussian pulse	required

posSineDriver(constantValue, amplitude, frequency, phase)

Produces a positive sinusoidal signal with some offset (constantValue), amplitude frequency and phase offset.

Parameters:

Name	Type	Description	Default
constantValue	float	vertical offset. The sine will oscillate around this value.	required
amplitude	float	amplitude of the sine wave	required
frequency	float	frequency of the sine	required
phase	float	phase of the sine in radians.	required

pulseDriver(constantValue, amplitude, period, cycle)

Produces a square pulse of certain period and cycle

Parameters:

Name	Type	Description	Default
constantValue	float	offset (vertical) of the pulse. The pulse amplitude will be added to this.	required
amplitude	float	amplitude of the pulse signal	required
period	float	period of the signal in seconds	required
cycle	float	duty cycle of the signal -- a fraction between [0 and 1].	required

sineDriver(constantValue, amplitude, frequency, phase)

Produces a sinusoidal signal with some offset (constantValue), amplitude frequency and phase offset.

Parameters:

Name	Type	Description	Default
constantValue	float	vertical offset. The sine will oscillate around this value.	required
amplitude	float	amplitude of the sine wave	required
frequency	float	frequency of the sine	required
phase	float	phase of the sine in radians.	required

stepDriver(constantValue, amplitude, timeStart, timeStop)

Get a step driver. It has amplitude between timeStart and timeStop and 0 elsewhere

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
timeStart	float	start of the pulse	required
timeStop	float	when the pulse ends	required

trapezoidDriver(constantValue, amplitude, timeStart, edgeTime, steadyTime)

Create Trapezoid driver. Has a rising and a falling edge.

Parameters:

Name	Type	Description	Default
constantValue	float	offset of the pulse (vertical)	required
amplitude	float	amplitude that is added on top of the constantValue	required
timeStart		start of the pulse	required
edgeTime	float	time it takes to reach the maximum amplitude	required
steadyTime	float	time it spends in a steady state	required