Online Materials Database – Boris Computational Spintronics

Material definitions used in Boris are available through a shared and user editable online materials database. This contains the most important material parameter values used for micromagnetic, charge and spin transport, and heat flow computations. Currently the database is small but the intention is to develop it over time as users send in entries to be added. For example these could include parameters used in publications, for materials under different growth conditions, interfaces, layer thicknesses, etc.

To obtain the latest material definitions in Boris, simply start the program and type the updatemdb console command. This will grab the material definitions in the table below and make them available for you to use.

To add a new computational mesh with given material parameters you can use the addmaterial command. The type of material will determine the type of computational mesh generated. For example the ferromagnetic type will generate a computational mesh with LLG/LLB solvers enabled. The conductor mesh type will generate a computational mesh with only the transport and heat solvers enabled, while the insulator mesh will only have the heat solver enabled (e.g. a substrate material).

Users can send in contributions using the requestmdbsync command after properly editing the entry (descriptions, DOI links references etc. – details in the manual). This command will place the entry in a holding database, and will be checked individually for validity before making it available in the publicly visible materials database.

Material parameters are listed below. Where applicable, these are given at room temperature where possible, unless otherwise specified. For definitions and descriptions hover mouse over the respective cell. Some parameter values have a DOI link enabled which gives the reference for it. You can sort the table by clicking on headers.

Name	Formula	Type	Contributor	g_rel	α	M_s (kA/m)	A (pJ/m)	D (mJ/m²)	J₁ (mJ/m²)	J₂ (mJ/m²)	K₁ (kJ/m³)	K₂ (kJ/m³)	ea₁	ea₂	T_c (K)	μ (μ_B)	σ (MS/m)	amr (%)	P⁽¹⁾	β⁽²⁾	D_e⁽³⁾ (m²/s)	β_D⁽⁴⁾	θ_SHA⁽⁵⁾	θ_iSHA⁽⁶⁾	fl_ST⁽⁷⁾	λ_sf⁽⁸⁾ (nm)	λ_J⁽⁹⁾ (nm)	λ_ϕ⁽¹⁰⁾ (nm)	G_i (PS/m²)	G_mix⁽¹¹⁾ (PS/m²)	K (W/mK)	ρ (kg/m³)	C (J/kgK)
SiO2	SiO2	insulator	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	0	-	-	-	-	-	-	-	-	-	-	-	-	-	1.4	2200	730
Ni	Ni	ferromagnetic	N/A	1.1	0.05	490	8	0	-	-	-5	0	i1 + j0 + k0	i0 + j1 + k0	628	0.6	14	2	0.44	0.01	0.0025	0.44	0	-	0	23	2.3	5.7	-	-	106	8908	440
Py	Ni80Fe20	ferromagnetic	N/A	1	0.02	800	13	0	-	-	0	0	-	-	870	1	6.7	3	0.4	0.06	0.0016	0.4	0	-	0	6.5	1.6	1.9	-	-	46.4	8740	430
Fe	Fe	ferromagnetic	N/A	1	0.001	1710	21	0	-	-	48	-10	i1 + j0 + k0	i0 + j1 + k0	1044	2.22	10	0.2	0.45	0.05	0.0023	0.45	0	-	0	9.5	2.2	4.4	-	-	79.5	7874	450
Co_hcp	Co	ferromagnetic	N/A	1.1	0.005	1440	31	0	-	-	410	140	i0 + j0 + k1	-	1360	1.72	17	1.9	0.42	0.004	0.0033	0.42	0	-	0	42	2.6	4.2	-	-	122	8920	420
MgO	MgO	insulator	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	0	-	-	-	-	-	-	-	-	-	-	-	-	-	42	3580	877
Si3N4	Si3N4	insulator	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	0	-	-	-	-	-	-	-	-	-	-	-	-	-	85	3220	680
Co/Pt	Co	ferromagnetic	N/A	1.3	0.1	600	10	-1.5	-	-	380	0	i0 + j0 + k1	-	1360	1.72	5	1.9	0.42	0.002	0.001	0.42	-	-	-	42	2	3.2	1 + i0.1	1.5 + i0.5	122	8920	420
Ir	Ir	metal	Callum MacKinnon	-	-	-	-	-	-	-	-	-	-	-	-	-	1.4	-	-	-	0.0002	-	0.02	0.02	-	0.5	-	-	-	0.35 + i0.045	146.5	22650	129.95
Co90Fe10/Ru	Co90Fe10	ferromagnetic	N/A	1.1	0.007	1300	15	0	-1	0	3.7	0	i1 + j0 + k0	-	1360	1.77	4	1	0.34	0.009	0.001	0.34	-	-	-	13	1.7	2.1	1 + i0.1	1 + i0.3	122	8800	420
Pt	Pt	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	7	-	-	-	0.0011	-	0.19	0.19	-	1.4	-	-	-	-	71.6	21452	125.6
Ru	Ru	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	1.5	-	-	-	0.003	-	0.006	0.006	-	4	-	-	-	-	117	12060	238
Ta	Ta	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	0.5	-	-	-	0.0001	-	-0.15	-0.15	-	1.9	-	-	-	-	57.5	16600	140
bW	beta-W	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	0.6	-	-	-	0.0002	-	-0.3	-0.3	-	2.4	-	-	-	-	173	19300	134
Pd	Pd	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	2.5	-	-	-	0.0005	-	0.01	0.01	-	5.5	-	-	-	-	72	11900	240
Au	Au	metal	N/A	-	-	-	-	-	-	-	-	-	-	-	-	-	20	-	-	-	0.004	-	0.003	0.003	-	35	-	-	-	-	310	19300	129
Cu	Cu	metal	Callum MacKinnon	-	-	-	-	-	-	-	-	-	-	-	-	-	22.2	-	-	-	0.0002	-	0.002	0.002	-	170	-	-	-	0.41 + i0.009	109	8900	612
CoFeB	Co60Fe20B20	ferromagnetic	N/A	1	0.02	810	20	-1.75	0	0	760	0	i0 + j0 + k1	i0 + j1 + k0	750	1.6	4	1.4	0.52	0.04	0.001	0.7	0	-	0	10	2	4	1 + i0.1	2 + i0.7	122	8800	420

(1) Current spin-polarisation defined as $P = (n^{\uparrow} - n^{\downarrow}) / (n^{\uparrow} + n^{\downarrow})$ .

(2) Non-adiabaticity parameter used for Zhang-Li STT. In the limit of long domain wall widths this is approximated as $\beta = \lambda _J^{2} / \lambda _{sf}^{2}$ .

(3) Electron diffusion constant, where the Einstein relation is $D _e = \mu _e k _B T / e$ , with electron mobility linked to electrical conductivity by $\sigma = n _{eff} e \mu _e$ . The effective density of states is given in terms of the Fermi energy as $n _{eff} = g(E _F) k _B T = (3 n / 2 E _F) k _B T$ .

(4) Diffusion spin-polarisation defined as $\beta _D = (l^{\uparrow} - l^{\downarrow}) / (l^{\uparrow} + l^{\downarrow})$ , where $l^{\uparrow}$ and $l^{\downarrow}$ are spin-dependent diffusion lengths. Values set to those of P if not known, but will not be correct in general.

(5) Spin-Hall angle. Can also be given in ferromagnetic layers, where it is used directly in the SOT added to the LLG/LLB equation, rather than in the spin transport solver. In this case it is an effective spin-Hall angle which depends on the exact multilayered stack composition, so it should refer specifically to a value used in a publication.

(6) Spin-Hall angle, but used for the inverse spin-Hall effect. Can be set to zero to disable the inverse spin-Hall effect in the spin transport solver, otherwise it should be the same as for the direct effect.

(7) Field-like SOT coefficient (ratio of field-like to damping-like SOT), used directly in the SOT added to the LLG/LLB equation, rather than in the spin transport solver. In this case the coefficient depends on the exact multilayered stack composition, so it should refer specifically to a value used in a publication.

(8) Spin-flip length, linked to the spin diffusion length by $\lambda _{sdl} = \lambda _{sf} \sqrt{1 - P \beta _D}$ . This is also linked to the electron diffusion constant by $\lambda _{sf} = \sqrt{\tau _{sf} D _e}$ .

(9) Exchange rotation length, linked to the exchange interaction energy between itinerant and localised electrons (s-d exchange interaction) by $\lambda _J = \sqrt{\hbar D _e / J}$ . For these, values between $J = 0.2 eV$ and $J = 0.4 eV$ were assumed.

(10) Spin dephasing length, obtained as $\lambda _{\phi} = \lambda _J \sqrt{l _{\perp} / l _L}$ . Here, $l _{\perp}$ and $l _L$ are the spin coherence and spin precession lengths respectively.

(11) Spin mixing conductance. The imaginary part is set to one 3rd of the real part if not known, as data in the literature on this is typically scarce.