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Switchable X-Ray Orbital Angular Momentum from an Artificial Spin Ice.
Justin S Woods1,2, Xiaoqian M Chen3,4, Rajesh V Chopdekar3
1Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA.
Physical Review Letters
|April 2, 2021
Summary
Artificial spin ices with topological defects can impart orbital angular momentum (OAM) to X-rays. This discovery enables reconfigurable X-ray optics for probing magnetic properties.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Optics
Background:
- Artificial spin ices (ASI) are magnetic metamaterials whose properties depend on geometry.
- X-ray photon orbital angular momentum (OAM) is an area of growing research interest.
Purpose of the Study:
- To investigate if ASI with topological defects can impart OAM to scattered X-rays.
- To explore the potential of ASI as reconfigurable X-ray optics.
Main Methods:
- Fabrication of a square ASI with a double edge dislocation.
- X-ray diffraction experiments to analyze scattered photons.
- Investigation of magnetic transitions under varying temperature and magnetic field.
Main Results:
- A double edge dislocation in ASI imparts OAM to scattered X-rays.
- The ASI equilibrates to an antiferromagnetic (AFM) ground state without magnetic frustration.
- X-ray diffraction yields photons with even and odd OAM at structural and AFM Bragg conditions, respectively.
- AFM OAM beams can be switched on/off via temperature and magnetic field variations.
Conclusions:
- ASIs with specific topological defects act as metasurfaces for X-ray optics.
- This technology allows for selective probing of electronic and magnetic properties.
- The OAM of X-rays can be controlled by the ASI's magnetic state.
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