BT7 3-Axis

Instrument Purpose

To provide an ultra-high flux thermal neutron beam for mapping complex magnetic and lattice structures and excitations, specifically optimized for small samples and weak signals in quantum materials.

The NCNR Advantage

• Unmatched Flux on Sample: Features a unique double-focusing monochromator and analyzer system that "concentrates" the neutron beam, providing significantly higher intensity than standard triple-axis instruments.
• Flexibility of tuning the resolution: Choices of up to four different collimations at each of location along the beam path (before and after the monochromator, after the sample, and after the analyzer), the momentum and energy resolutions can vary by orders of magnitudes with different measurement requirements.
• Advanced Polarization Analysis: Equipped with state-of-the-art ³He spin filters, allowing researchers to unambiguously separate magnetic scattering from lattice signals.
• Extreme Environment Compatibility: Designed with a sample table and flexible geometry to accommodate the whole range of sample equipment in the NCNR fleet, able to accommodate the largest superconducting magnets, Dilution Fridges, high-power furnace, and high-pressure cells.
• Velocity selector: The velocity selector is specifically engineered for thermal neutron instruments. It effectively suppresses higher‑order wavelength contamination in the incident beam and correspondingly reduces the overall background level.

Research Domains

• Quantum Materials: Exploring topological insulators, Dirac/Weyl semimetals, and quantum spin liquids.
• High-Temperature Superconductivity: Mapping spin fluctuations and "intertwined orders" in High-Tc superconductors.
• Functional Magnetics: Investigating multiferroics and skyrmion-hosting materials for next-generation spintronics.
• Energy Materials: Measuring lithium-ion diffusion dynamics in battery cathode materials.

What You Can Measure

• Single crystal magnetic structure: Mapping the focused area of the Bragg peaks, especially for small sample (or thin film) with low ordered moments and/or complicated structures.
• Detailed Spin-Wave Dispersion: Complete mapping of magnetic exchange interactions.
• Phonon Dispersion: Understanding thermal transport and lattice stability.
• Polarized Neutron Scattering: Directly isolating the magnetic components from the structural components of a signal.