Magnetic, Electronic, and Optical Studies of Gd-Doped WO: A First Principle Study.

Tungsten trioxide (WO) is mainly studied as an electrochromic material and received attention due to N-type oxide-based semiconductors. The magnetic, structural, and optical behavior of pristine WO and gadolinium (Gd)-doped WO are being investigated using density functional theory. For exchange-correlation potential energy, generalized gradient approximation (GGA+U) is used in our calculations, where U is the Hubbard potential. The estimated bandgap of pure WO is 2.5 eV. After the doping of Gd, some states cross the Fermi level, and WO acts as a degenerate semiconductor with a 2 eV bandgap. Spin-polarized calculations show that the system is antiferromagnetic in its ground state. The WO material is a semiconductor, as there is a bandgap of 2.5 eV between the valence and conduction bands. The Gd-doped WO's band structure shows few states across the Fermi level, which means that the material is metal or semimetal. After the doping of Gd, WO becomes the degenerate semiconductor with a bandgap of 2 eV. The energy difference between ferromagnetic (FM) and antiferromagnetic (AFM) configurations is negative, so the Gd-doped WO system is AFM. The pure WO is nonmagnetic, where the magnetic moment in the system after doping Gd is 9.5599575 μB.