Related Experiment Video
Updated: Aug 27, 2025

Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Optically controllable magnetism in atomically thin semiconductors
Kai Hao1, Robert Shreiner1,2, Andrew Kindseth1,2
1Pritzker School of Molecular Engineering, University of Chicago , Chicago, IL 60637, USA.
Abstract:
We report evidence that ferromagnetic order in electrostatically doped, monolayer transition metal dichalcogenide (TMD) semiconductors can be stabilized and controlled at zero magnetic field by local optical pumping. We use circular dichroism (CD) in reflectivity from excitonic states as a spatially resolved probe of charge-carrier spin polarization. At electron densities n ~ 1012 cm-2, a diffraction-limited, circularly polarized optical pump breaks symmetry between oppositely polarized magnetic states and stabilizes long-range magnetic order, with carrier polarization exceeding 80% over an 8 μm by 5 μm extent. In time-resolved measurements with pulsed optical excitation, we observe that magnetic interactions amplify the initial pump-induced spin polarization by more than an order of magnitude. The optical control of magnetism with local optical pumps will unlock advancements in spin and optical technologies and provides a versatile tool in the study of correlated phases in two-dimensional electron gases.
Related Concept Videos
Ferromagnetism
Diamagnetism
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Fermi Level Dynamics
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Paramagnetism
Biasing of Metal-Semiconductor Junctions
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
Atomic Nuclei: Nuclear Relaxation Processes

