Figure 1

Device cross section in $x,z$ direction. Top and bottom Al${}_{0.9}$Ga${}_{0.1}$As barrier thickness is 60 nm, GaAs quantum well thickness is 15 nm, and Al${}_{0.9}$Ga${}_{0.1}$As barrier thickness is 1 nm. A channel is 1.2 $\mu \mathrm{m}$ long and 7.5 $\mu \mathrm{m}$ wide. An assumed electron density in two-dimensional electron gas (2DEG) is $2.0\times {10}^{10}{\mathrm{cm}}^{-2}$.Reuse & Permissions

Figure 2

Schematic of the Fermi surfaces of the bilayer system containing populations of symmetric and anti-symmetric state separated in energy by a single-particle tunneling term, ${\Delta }_{\mathrm{SAS}}$.Reuse & Permissions

Figure 3

Plot of the height of the interlayer conductance as a function of the interlayer exchange enhancement $S$ at interlayer bias $V_T-V_B=10\mathrm{nV}$. In the inset, we plot of the height of the interlayer conductance normalized to the non-interacting conductance ($S=1$) as a function of $S$ with the same $x$-axis. We clearly see that the height of the interlayer conductance follows an $S^2$ dependence. The single-particle tunneling amplitude $t={\Delta }_{\mathrm{SAS}}/2=1\mu \mathrm{eV}$.Reuse & Permissions

Figure 4

Plot of the differential conductance of the bilayer system at $S=4$ (orange triangle), $S=2$ (blue circle), and $S=1$ (opened rectangular) as a function of interlayer bias $V_B-V_T$ at 0 K. In the inset, the same plot in negative interlayer bias with same $y$ axis is plotted with $x$-axis in logarithmic scale. In small bias window, almost constant interlayer transconductance is observed. After the interlayer bias reaches $V_{\mathrm{INT}}\approx 10$ $\mu \mathrm{V}$, an abrupt drop in transconductance can be seen in the interacting electron cases of $S=2,4$. We plot the current vs bias voltage for each enhancement factor in the inset.Reuse & Permissions

Figure 5

Pseudospin polarization vs current. The quantities are expressed in units of the value of $m_x$ at zero bias ($m_0$). The points in this plot correspond to the same points that appear in the inset of current vs bias voltage in Fig. 4. For zero current, the pseudospin is in the $\widehat{x}$ direction and has a value close to $m_0={\nu }_{0}St$. $m_x$ decreases monotonically, $m_z$ increases monotonically, and $m_y$ increases nearly monotonically before saturating at the largest field values. The arrow in the plot indicates the direction in which a bias voltage increases.Reuse & Permissions

Figure 6

Pseudospin polarization vs bias voltage. The quantities are expressed in units of the value of $m_x$ at zero bias ($m_0$). The inset of this plot clearly shows that $m_z$ increases monotonically with bias voltage which eventually causes the current to decrease. The $|{\mathbf{m}}_{xy}|$ decreases only slowly with bias voltage because of the compensating effects of pseudospin rotation toward the $\widehat{z}$ direction and an increase in the overall pseudospin polarization. There is no steady-state solution to the self-consistent transport equations beyond the largest bias voltage plotted here, because the pseudospin orientation ${\phi }_{\mathrm{ps}}$ has reached $\pi /2$.Reuse & Permissions

Figure 7

Quasiparticle layer-polarization parameter $\sigma$ as a function of interlayer bias. When the source-drain bias exceeds around $\sim 10$ $\mu \mathrm{V}$, the mismatch match between subband energy levels exceeds the width of the conductance peak, $\sigma$ increases rapidly, and the $\widehat{x}-\widehat{y}$-plane pseudospin polarization and critical current decrease. The inset shows the same data in logarithmic scale to emphasize the low-bias behavior.Reuse & Permissions