M-STAR: Magnetism second target advanced reflectometer at the Spallation Neutron Source

Area of Science:

• Materials Science and Engineering
• Condensed Matter Physics
• Nanoscience and Nanotechnology

Background:

• Next-generation neutron reflectometry is crucial for characterizing complex nanostructures.
• Existing techniques face limitations in sample size and probing capabilities for buried interfaces.

Purpose of the Study:

• To introduce M-STAR, a novel polarized neutron reflectometer with enhanced capabilities for nanoscience and spintronics.
• To enable routine studies on millimeter-sized, atomically thin samples under various in situ conditions.
• To expand the accessible range of wavevector transfer (Q) for advanced scattering measurements.

Main Methods:

• Utilizes a new focusing guide concept for small sample optimization.
• Incorporates a hybrid pulse-skipping chopper for constant geometry experiments.
• Enables specular, off-specular, grazing incidence small-angle neutron scattering (GISANS), and grazing incidence diffraction (GID).

Main Results:

• Optimized for samples as small as 2x2 mm², enabling studies on atomic-scale thicknesses.
• Provides a broad Q range (up to 0.3 Å⁻¹) for versatile measurements.
• Facilitates in situ application of magnetic/electric fields, light, and temperature.
• Offers improved GID for probing out-of-plane magnetic moments and in-plane structures.
• Introduces inelastic grazing incidence scattering for near-surface dynamics.

Conclusions:

• M-STAR significantly advances capabilities in polarized neutron reflectometry.
• It empowers routine high-resolution studies on challenging nanosystems and device-like structures.
• The instrument is positioned to lead in high-resolution polarized reflectometry and related surface/interface studies.