Figure 1

Different types of Mott spin junctions. The spin states of the source (top electrode) and drain are indicated by thick red arrows. The spin orientation of the propagating electrons is indicated with green arrows. The various spin states depicted in Fig. 1 are simplified to illustrate the principle of operation of the junctions. Generally, we expect that the spin state of the drain (red arrow) is also modified. In (a) (a two-magnet Mott spin junction), the spin state of the source (top electrode, red) is the same as the spin state of the drain (bottom electrode, red) and the current (green) flowing through the junction amounts to \({I}_{ \rightarrow }^{ \rightarrow }\). (b): When the spin state of the drain is reversed, a current asymmetry \(\tfrac{{I}_{ \rightarrow }^{ \rightarrow }-{I}_{ \leftarrow }^{ \rightarrow }\,}{{I}_{ \rightarrow }^{ \rightarrow }+{I}_{ \leftarrow }^{ \rightarrow }}\) is obtained. (c) In the one-magnet-only Mott spin junction, the source electrode emits an equal number of electrons with the opposite spin state, but the exchange scattering⁶ with the spin state of the drain selects a well-defined spin state for both transmitted and backscattered electrons. The corresponding spin polarisation can be measured by spin polarimetry (for convenience, the coordinate system used in the paper is indicated).