Related Experiment Video
Updated: Apr 3, 2026
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
10.6K
Spin-Based Mach-Zehnder Interferometry in Topological Insulator p-n Junctions
Roni Ilan1, Fernando de Juan1,2, Joel E Moore1,2
1Department of Physics, University of California, Berkeley, California 94720, USA.
Physical Review Letters
|September 16, 2015
Summary
A magnetic field transforms a topological insulator p-n junction into an electronic interferometer. This novel spintronic device offers tunable transmission and acts as a spin filter, probing spin-momentum locking effects.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Topological insulators possess unique spin-momentum locked surface states crucial for charge transport.
- These surface states enclose an insulating bulk, enabling exotic electronic phenomena.
Purpose of the Study:
- To investigate the behavior of topological insulator p-n junctions under magnetic fields.
- To demonstrate the creation of an electronic Mach-Zehnder interferometer using these junctions.
- To explore the potential of this system as a tunable spintronic device.
Main Methods:
- Utilizing a topological insulator p-n junction.
- Applying a magnetic field to induce interference.
- Measuring the transmission and spin polarization of the electronic current.
Main Results:
- A magnetic field induces an electronic Mach-Zehnder interferometer in the topological insulator surface state.
- The junction's transmission is tunable from zero to unity with high interference visibility.
- The reflected and transmitted currents exhibit opposite spin polarization, functioning as a spin filter.
Conclusions:
- The proposed setup realizes a novel and highly tunable spintronic device.
- This system allows for direct probing of spin-momentum locking effects in topological insulator surface states via transport experiments.
Related Concept Videos
01:27Biasing of Metal-Semiconductor Junctions
835
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
835
01:24Metal-Semiconductor Junctions
1.4K
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The...
1.4K
01:11P-N junction
1.7K
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
1.7K
01:16Biasing of P-N Junction
2.6K
The operation of a p-n junction diode involves various biasing conditions, including forward bias, reverse bias, and equilibrium.
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
2.6K