Spin-photovoltaic effect in quantum wires due to intersubband transitions

We consider the current induced in a quantum wire by external electromagnetic radiation. The photocurrent is caused by the interplay of spin-orbit interaction (Rashba and Dresselhaus terms) and an external in-plane magnetic field. We calculate this current using a Wigner functions approach, taking into account radiation-induced transitions between transverse subbands. The magnitude and the direction of the current depend on the Dresselhaus and Rashba constants, strength of magnetic field, radiation frequency, and intensity. The current can be controlled by changing some of these parameters.

Figure 1

(Color online) Quantum wire with an applied magnetic field in the $(x,y)$ plane, and irradiated by an electromagnetic wave linearly polarized in the $y$ direction.

Figure 2

(Color online) Dispersion relations (two lowest spin-splitted subbands) calculated for (a) $B_x=2\mathrm{T}$, $B_y=2\mathrm{T}$ and (b) $B_x=2\mathrm{T}$, $B_y=-2\mathrm{T}$. These plots were obtained using the parameters values: $m^{*}=0.067m_e$, $g^{*}=-0.44$, ${\alpha }_0=0.5\times {10}^{-11}\mathrm{eV}\mathrm{m}$, ${\beta }_{0,0}=0.84\times {10}^{-11}\mathrm{eV}\mathrm{m}$, ${\beta }_{1,0}=0.36\times {10}^{-11}\mathrm{eV}\mathrm{m}$, ${ϵ}_1-{ϵ}_0=3.64\mathrm{meV}$.

Figure 3

(Color online) The different subband transition due to the interaction with an electro-magnetic wave are sketched. The interaction causes some electrons to change the direction of the velocity.

Figure 4

(Color online) Current through the wire as a function of photon energy $\hslash \omega$ for (a) $B_x=2\mathrm{T}$, $B_y=2\mathrm{T}$ and (b) $B_x=2\mathrm{T}$, $B_y=-2\mathrm{T}$. The parameters values are as in Fig. 2, $E_y=200\mathrm{V}∕\mathrm{m}$.

Figure 5

(Color online) Transitions in the regions of photocurrent peaks for $B_x=2\mathrm{T}$, $B_y=-2\mathrm{T}$. The energy spectrum and difference energies are shown in the top and bottom panels, respectively. Horizontal lines in the bottom panel correspond to excitation energies in peak regions; vertical arrows in the top panel denote transitions when electron velocity direction changes.

Figure 6

(Color online) Spin current components for $B_x=2\mathrm{T}$, $B_y=-2\mathrm{T}$ at $x=0$.