Refractive index of Ni-Fe (Nickel-iron alloy, Permalloy)

import lightsmith as ls

# Ni-Fe (Nickel-iron alloy, Permalloy): Tikuišis et al. 2017: n,k 0.193–1.69 µm; gold-coated, 150 nm
ni_fe = ls.fetch_refractiveindex("other", "Ni-Fe", "Tikuisis_gold150nm", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(ni_fe.range_nm)  # (193, 1690) nm
eps = ni_fe.eps([633])  # complex permittivity

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_5c855d4f890d/lightsmith"
ni_fe = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(ni_fe.source)  # citation and provenance travel with the data

# ... load ni_fe as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=ni_fe)],
    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