Axial current driven by magnetization dynamics in Dirac semimetals

We theoretically study the axial current ${\mathit{j}}_5$ (defined as the difference between the charge current with opposite helicity) in the magnetic insulator/doped Dirac semimetal using microscopic theory. In the Dirac semimetal, the axial current is induced by the magnetization dynamics, which is produced from the proximity effect of the magnetization of the magnetic insulator. We find that the induced axial current can be detected by using ferromagnetic resonance or the inverse spin Hall effect and can be converted into charge current with no accompanying energy loss. These properties make the Dirac semimetal advantageous for application to low-consumption electronics with new functionality.

Figure 1

(a) Schematic illustration of the CSE. (b) A setup of the doped DS/MI junction for the axial current generation. Since the magnetization in the MI can penetrate into the doped DS in the length scale $\lambda$, the effective localized spin $\mathit{S}$ can be generated in the doped DS, as shown in the gray area.

Figure 2

(a) Schematic diagram of the axial current generation and ferromagnetic resonance. (b) Schematic illustration of the torque acting the magnetization at the interface between the MI and the thin film of the doped DS in Fig. 2. The green arrow denotes field-driven torque and the orange and red arrow represent the damping torque.

Figure 3

Geometry for ${\mathit{j}}_5^{\mathrm{D}}$ in the MI/doped DS/NM junction.