  This work theoretically and analytically demonstrates the magnetic
field-induced spectral radiative properties of photonic metamaterials
incorporating both Indium Antimonide (InSb) and Tungsten (W) in the terahertz
(THz) frequency regime. We have varied multiple factors of the nanostructures,
including composite materials, layer thicknesses and surface grating fill
factors, which impact the light-matter interactions and in turn modify the
thermal emission of the metamaterials. We have proposed and validated a method
for determining the spectral properties of InSb under an applied direct current
(DC) magnetic field, and have employed this method to analyze how these
properties can be dynamically tuned by modulating the magnitude of the field.
For the first time, we have designed an InSb-W metamaterial exhibiting unity
narrowband emission which can serve as an emitter for wavelengths around 55
$\mu$m (approximately 5.5 THz). Additionally, the narrowband emission of this
metamaterial can be magnetically tuned in both bandwidth and peak wavelength
with a normal emissivity close to unity.
