NGD PBR

Instrument Purpose

To provide depth-resolved structural and magnetic profiles of thin films and multilayers with sub-nanometer precision, with capabilities for full polarization in high magnetic fields, for the most demanding investigations of quantum materials and spintronic devices.

The NCNR Advantage

• Dedicated Polarization Analysis: PBR is purpose-built for Polarized Neutron Reflectometry (PNR). It can independently control the spin state of incident and reflected neutrons, allowing researchers to obtain depth profiles of both the structure and vector magnetization in multilayer films.
• High-Field Capability: PBR supports a superconducting magnet up to 3 T, enabling measurements of field-dependent magnetic transitions.
• Low-Background Cold Source: Located on the NGD cold neutron guide, the instrument benefits from a high-flux, low-noise environment, enabling the measurement of reflectivity down to 10^-7, essential for probing ultra-thin films.
• In Situ Measurement Capability: PBR accommodates a wide range of sample environments, including high field magnets and low temperature refrigerators, that are optimized for in situ measurements of thin films in response to variations in temperature, magnetic field, electric field, and other stimuli.

Research Domains

• Spintronics: Mapping the profile of the vector magnetization in spin-based electronic model systems and prototypes such as Magnetic Tunnel Junctions (MTJs) and Giant Magnetoresistance (GMR) sensors.
• Quantum Materials: Probing proximity effects at interfaces in layered materials that include topological insulators, frustrated low-dimensional magnets, and Dirac and Weyl Semimetals.
• Magneto-Ionics: Characterizing the voltage-induced magnetization change in coupled magnetostrictive layers and the motion of O, H, and N ions in magneto-ionic device prototypes.
• Superconductors: Obtaining the penetration depth profile in conventional spin-singlet and unconventional spin-triplet superconducting films.

What You Can Measure

• Specular Reflectivity: Absolute determination of structural and magnetic layer thicknesses (2 nm to 200 nm), density, and roughness.
• Magnetic Depth Profiling: Determining the direction and magnitude (i.e., vector magnetization) with sub-nanometer depth resolution.
• Interface Roughness: Quantifying the "sharpness" of the structural and magnetic transitions between layers.