# Technical Data Extraction: Current Density and Streamline Plots
This document provides a detailed technical extraction of the data contained in the provided image, which consists of two side-by-side scientific plots (labeled 'f' and 'h') representing physical simulations of current flow in a nanostructure.
## 1. General Metadata
* **Language:** English
* **Subject Matter:** Condensed Matter Physics / Nanotechnology (likely related to Graphene or Topological Insulators given the $K_2$ and $E_F$ notation).
* **Components:** Two heatmaps with overlaid vector streamlines and associated color bars.
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## 2. Plot (f) Analysis
### Header and Labels
* **Title:** (f) $K_2$: $E_F = +0.035t$
* **Y-Axis Title:** width (nm)
* **Y-Axis Markers:** -10, 0, 10
* **X-Axis Title:** length (nm)
* **X-Axis Markers:** -40, -20, 0, 20, 40
### Color Bar (Legend)
* **Location:** Right side of plot (f).
* **Scale:** Linear heatmap ranging from white (0.0) to dark orange/brown (approx. 0.5).
* **Markers:** 0.0, 0.2, 0.4.
### Data Trends and Components
* **Heatmap (Background):** Represents a scalar quantity (likely current density magnitude). The intensity is highest (dark orange) on the right side (length $\approx$ 40 to 50 nm) and shows periodic "hotspots" or nodes along the center line ($y=0$) at approximately $x = -30, 0, 30$ nm.
* **Streamlines (Blue Lines):** Represent the direction of flow.
* **Trend:** The flow enters from the right and moves toward the left.
* **Behavior:** On the right side ($x > 30$), there is significant turbulence or vortex-like behavior where lines curve sharply. As the flow moves toward the left ($x < 0$), the streamlines become more laminar and parallel to the x-axis.
* **Directional Indicator:** A long black arrow at the bottom of the plot points from right to left (from $x \approx 40$ to $x \approx -50$), confirming the net direction of transport.
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## 3. Plot (h) Analysis
### Header and Labels
* **Title:** (h) $K_2$: $E_F = -0.035t$
* **Y-Axis Title:** width (nm)
* **Y-Axis Markers:** -10, 0, 10
* **X-Axis Title:** length (nm)
* **X-Axis Markers:** -40, -20, 0, 20, 40
### Color Bar (Legend)
* **Location:** Right side of plot (h).
* **Scale:** Linear heatmap ranging from white (0.0) to dark orange/brown (approx. 0.6).
* **Markers:** 0.0, 0.2, 0.4, 0.6.
### Data Trends and Components
* **Heatmap (Background):** Compared to plot (f), the intensity is significantly lower across the left half of the device. The signal is concentrated almost entirely on the right side ($x > 10$ nm).
* **Streamlines (Blue Lines):**
* **Trend:** Flow is concentrated on the right.
* **Behavior:** There are distinct circular vortices visible at $x \approx 25$ nm, centered at $y \approx \pm 5$ nm. The flow appears "trapped" or recirculating on the right side. The streamlines on the left side ($x < 0$) are extremely faint, indicating very low current density.
* **Directional Indicator:** A long black arrow at the bottom points from right to left, identical to plot (f), indicating the intended direction of transport despite the low intensity on the left.
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## 4. Comparative Summary
| Feature | Plot (f) | Plot (h) |
| :--- | :--- | :--- |
| **Fermi Energy ($E_F$)** | $+0.035t$ (Positive/Electron-like) | $-0.035t$ (Negative/Hole-like) |
| **Transport Efficiency** | High; current spans the full length. | Low; current is localized to the right. |
| **Flow Pattern** | Laminar on the left, turbulent on right. | Strong vortices on the right; stagnant on left. |
| **Peak Intensity** | $\approx 0.5$ | $\approx 0.6$ (but more localized) |
**Conclusion:** The change in the sign of the Fermi Energy ($E_F$) from positive to negative causes a transition from a relatively smooth, through-flowing current (f) to a localized, vortex-heavy state with poor transmission to the left side of the nanostructure (h).
