  Two-dimensional (2D) magnetic materials are essential for the development of
the next-generation spintronic technologies. Recently, layered van der Waals
(vdW) compound MnBi2Te4 (MBT) has attracted great interest, and its 2D
structure has been reported to host coexisting magnetism and topology. Here, we
design several conceptual nanodevices based on MBT monolayer (MBT-ML) and
reveal their spin-dependent transport properties by means of the
first-principles calculations. The pn-junction diodes and sub-3-nm pin-junction
field-effect transistors (FETs) show a strong rectifying effect and a spin
filtering effect, with an ideality factor n close to 1 even at a reasonably
high temperature. In addition, the pip- and nin-junction FETs give an
interesting negative differential resistive (NDR) effect. The gate voltages can
tune currents through these FETs in a large range. Furthermore, the MBT-ML has
a strong response to light. Our results uncover the multifunctional nature of
MBT-ML, pave the road for its applications in diverse next-generation
semiconductor spin electric devices.
