  Spin filtering is a fundamental operation in spintronics, enabling the
generation and detection of spin-polarized carriers. Here, we proposed and
theoretically demonstrated that a 3d transition metal (TM) doped silicon
quantum dot (SiQD) is a suitable candidate for spin filter device at room
temperature. Using density functional theory (DFT), we investigate the
structure, electronic properties, and magnetic behavior of TM-SiQD. Our
calculations demonstrate that Mn-doped SiQD exhibits the highest stability. The
designed spin-filter device using Mn-doped SiQD shows a spin-filtering
efficiency of 99.9% at 300K electrode temperature along with very high
conductance. This remarkable efficiency positions it as a promising candidate
for room-temperature spintronic devices.
