 Under negative gate voltages (VG < 0) which shift down the material's Fermi level (EF) into spin-flip gap Δ2 in valence band, BMS conducts with carriers fully spin up polarized, while the conducting carriers change to be fully spin down polarized when positive gate voltages (VG > 0) push the Fermi level (EF) up into spin-flip gap Δ3 in conduction band.BMS is expected to be applied as bipolar field eﬀect spin filter and field eﬀect spin valve, or entangled electron detectors and separators.A number of BMS materials have been theoretically predicted, such as MnPSe3 nanosheets, Heusler alloys FeVXSi (X = Ti, Zr), double perovskites A2CrOsO6 (A=Ca, Sr, Ba) and DPP-based metal–organic framework.