TRIAX Triple-Axis Spectrometer

Determination of dynamics in solids in the meV range and low temperature magnetic ordering in single crystals.

TRIAX is a thermal triple-axis spectrometer and is the only inelastic neutron spectrometer on a university campus in the United States. Triple-axis spectrometers are highly flexible instruments that were designed to study the dynamic response of solids in a typical energy range of ~1 meV up to tens of meV. This enables the study of excitations such as phonons and magnons. TRIAX has also been extensively used for single crystal diffraction — especially of magnetic systems — and for quasielastic studies of magnetic fluctuations. As with any neutron instrument, inelastic studies benefit from larger crystals, but some information can be obtained from powders. Elastic experiments have been performed on TRIAX with crystals smaller than 10 mg or even with epitaxial thin films.

Researchers utilize neutron diffraction on TRIAX in a wide range of topical areas:

• Determination of magnetic structure in single crystal specimen

• Phonons, magnons, crystal field transitions, magnetic fluctuations

• Functional materials

• Frustrated magnets

• Topological semimetals

• Multiferroics

• Quantum critical point materials

• Quantum spin liquid candidates

• Superconductors

• Magnetism in low dimensional systems

• High entropy oxides and other compounds

• Beam spectrum: Thermal

• Monochromators: vertically focusing PG (002), Cu (220), and Si (111)

• Analyzer: flat PG (002)

• Filtering: PG, Be, Si

• Collimation: Source-Monochromator: 60´, 43´, 29´, 14´

Monochromator-Sample: 60´, 40´, 20´, 10´

Sample-Analyzer: 80´, 40´, 20´, 10´

Analyzer-Detector: 80´, 40´, 20´, 10´

• Scattering angle: up to 120°

• Software interface: SPICE (LabVIEW-based, developed at Oak Ridge National Laboratory)

• Sample environment: continuous temperature control between 5K and 700K