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Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow
Published on: April 30, 2018
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Current Flow in the Bubble and Stripe Phases.
B Friess1, V Umansky2, K von Klitzing1
1Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Physical Review Letters
|April 26, 2018
Summary
Surface acoustic waves reveal that current-induced changes in ordered electron systems are local, not bulk phenomena. This challenges conventional transport measurements and highlights acoustic methods for studying inhomogeneous phases.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Mesoscopic Physics
Background:
- Spontaneous ordering of spins and charges into geometric patterns is observed in various material systems.
- Interactions between ordered phases and itinerant electrons under external current are crucial for understanding charge ordering and pattern manipulation.
- Conventional transport methods offer indirect information about bulk properties due to complex current distributions in inhomogeneous ground states.
Purpose of the Study:
- To investigate the impact of external currents on broken-symmetry phases in two-dimensional electron systems.
- To compare the effectiveness of surface acoustic waves versus conventional transport methods in probing these phases.
- To analyze the bubble and stripe phases in GaAs/AlGaAs heterostructures as model systems.
Main Methods:
- Utilizing surface acoustic waves to probe bulk properties of the material.
- Applying unidirectional current to induce changes in the electron system.
- Measuring sound propagation and voltage drop along sample edges for comparison.
Main Results:
- A discrepancy was observed between sound propagation (bulk) and voltage drop (edge) measurements under current drive.
- Current-induced modifications in resistive transport measurements were found to be a local phenomenon.
- The majority of the sample remained unaltered by the applied current.
Conclusions:
- Surface acoustic wave measurements provide direct insight into bulk properties, unlike conventional methods.
- Current-induced effects on ordered electron phases are more localized than previously assumed.
- Acoustic measurements offer intrinsic advantages for studying inhomogeneous phases in electronic materials.
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