Abstract: Transition metal dichalcogenide (TMD)-based spintronics devices, each including a TMD thin film layer, a first gate electrode, a first insulating layer sandwiched between the TMD thin film layer and the first gate electrode, a second gate electrode, and a second insulating layer sandwiched between the TMD thin film layer and the second gate electrode. Such a device, when also including a source electrode and a drain electrode, functions as a spin filter. On the other hand, when also including one source electrode and two drain electrode terminals, such a device functions as a spin separator. Also disclosed are methods of using the above-described TMD-based spintronics devices.