Optical constants

Refractive index of Co (Cobalt)

Johnson and Christy 1974: n,k 0.188–1.937 µm

Data: tabulated nk
Range: 0.188–1.937 µm
Points: 49
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 2.1396
Extinction coefficient k: 3.984

Permittivity ε₁: -11.2944
Permittivity ε₂: 17.0483

Absorption coefficient α: 852015 cm⁻¹
Penetration depth δ = λ/(2πk): 23.4738 nm

Abbe number V_d: —
Chromatic dispersion dn/dλ: 1.71429 µm⁻¹

Group index n_g: 1.13229
Group velocity dispersion: — fs²/mm

Dispersion parameter D: — ps/(nm·km)
Photon energy: 2.11001 eV

ε = (n + ik)², α = 4πk/λ, n_g = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith

import lightsmith as ls

# Co (Cobalt): Johnson and Christy 1974: n,k 0.188–1.937 µm
co = ls.fetch_refractiveindex("main", "Co", "Johnson", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(co.range_nm)  # (188, 1937) nm
eps = co.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_bc028358841b/lightsmith"
co = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(co.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (co/johnson-christy-1974).

# ... load co as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=co)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength

Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).

Materials guide Open a sphere of it in Studio Quick start Ask the community

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Comments and conditions

Room temperature

References

P. B. Johnson and R. W. Christy. Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd. Phys. Rev. B 9, 5056-5070 (1974)

doi:10.1103/physrevb.9.5056 Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd, Physical Review B (1974)

Cite

P. Johnson and R. Christy. Optical constants of transition metals: Ti, V, Cr, Mn, Fe, Co, Ni, and Pd. Physical Review B, 9, 5056-5070 (1974), doi:10.1103/physrevb.9.5056; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

49 rows as published

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

Co (Cobalt), Johnson and Christy 1974: n,k 0.188–1.937 µm: n and k versus wavelength
λ (µm)	n	k
0.188	1.16	1.59
0.192	1.21	1.63
0.195	1.26	1.67
0.199	1.29	1.71
0.203	1.32	1.75
0.207	1.36	1.78
0.212	1.38	1.82
0.216	1.41	1.84
0.221	1.43	1.85
0.226	1.45	1.86
0.231	1.47	1.87
0.237	1.47	1.89
0.243	1.46	1.91
0.249	1.45	1.93
0.255	1.45	1.97
0.262	1.44	2.01
0.269	1.44	2.04
0.276	1.44	2.09
0.284	1.44	2.14
0.292	1.44	2.19
0.301	1.44	2.25
0.311	1.44	2.31
0.32	1.45	2.37
0.332	1.46	2.44
0.342	1.48	2.52
0.354	1.49	2.61
0.368	1.5	2.71
0.381	1.53	2.82
0.397	1.57	2.93
0.413	1.61	3.05
0.431	1.67	3.17
0.451	1.74	3.28
0.471	1.81	3.41
0.496	1.88	3.55
0.521	1.97	3.68
0.549	2.05	3.82
0.582	2.13	3.96
0.617	2.19	4.11
0.659	2.25	4.27
0.704	2.31	4.45
0.756	2.4	4.64
0.821	2.53	4.88
0.892	2.65	5.16
0.984	2.78	5.5
1.088	2.94	5.88
1.216	3.17	6.31
1.393	3.42	6.77
1.61	3.61	7.26
1.937	3.87	7.79

Optical transmission calculator

Free-standing sample in vacuum, normal incidence

Transmittance T: —
Reflectance R: —

Fresnel reflection calculator

R_p: —
R_s: —
R = (R_p+R_s)/2: —
Phase φ_p: —
Phase φ_s: —
Brewster angle θ_B: —
Critical angle θ_C: —

Co (Cobalt): all datasets

Experimental data

Models and simulations

Werner et al. 2009: DFT calculations; n,k 0.0176–2.48 µm n,k 0.01759–2.48 µm

About Co (Cobalt)

Cobalt (Co) is a hard, lustrous, silver-gray metal found in the Earth's crust and commonly obtained as a byproduct of nickel and copper mining. It has a face-centered cubic crystal structure and is known for its high melting point, good thermal conductivity, and magnetic properties. Cobalt is widely used in a variety of applications including superalloys for jet engines and gas turbines, permanent magnets, and rechargeable batteries. Cobalt-based blue pigments have also been historically significant for ceramics and glass. On a smaller scale, but of considerable technological interest, cobalt is also used as a dopant in semiconductors and in certain types of stainless steel. From an environmental standpoint, cobalt can be toxic in high concentrations, necessitating safe handling and disposal practices. Recently, cobalt has gained significant attention for its role in lithium-ion batteries, leading to efforts for ethical sourcing and recycling due to human rights concerns related to its mining. In summary, cobalt is a versatile metal essential for modern technology, whose complex supply chain has made it a focus of ongoing sustainability and human rights initiatives.

More about Co (Cobalt) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/Co/nk/Johnson.yml
ID: ds_bc028358841b
API: /v1/datasets/ds_bc028358841b

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