Dimensional Extreme Magnetic Neutron Diffractometer
Mission Statement
Exploring nuclear and magnetic structures as a function of temperature, pressure, magnetic field, and electric field.
Instrument Description
The Dimensional Extreme Magnetic Neutron Diffractometer (DEMAND) has two modes of operation. Four-circle mode with the χ circle goniometer can operate with a closed-cycle-refrigerator (4–800 K) that allows a pressure cell (0-10 GPa), or a permanent magnet (0-0.9 T), and electric field. Two-axis mode allows extreme sample equipment cryomagnet (0-6 T), 3He insert and dilution refrigerators (0.05-300 K). Both modes can have an unpolarized and polarized neutron beam that can be switched by automated elevator device. The current detector has three Anger camera modules stacked vertically to cover 16° (horizontally) x 48° (vertically). The detector sits on the 2Θ rotation arm to cover the scattering angle range of 3° < 2Θ < 155°. A multilayer-[110]-wafer silicon monochromator with the reflection from HHL planes ensures sharp diffraction peaks in specified ranges of detector angles by control of the horizontal radius of curvature. Any HHL planes can be set in Bragg position, but only the (331), (220) with (440), and (111) with (333) reflections are of practical interest. For the fixed monochromator angle of 47.5°, these reflections provide principal incident wavelengths of 1.005 Å, 1.546 Å, and 2.541 Å, respectively. A PC-based LabView system provides user-friendly diffractometer control and data acquisition. The beam size is 6.3 mm in diameter, and the minimum measured crystal size is 0.02 mm3. The maximum crystal dimension is usually limited to 5 mm. The flux on the sample can be up to 2.2 × 107 n/cm2/s. The horizontal bending of the monochromator can be changed to optimize the Q-resolution or flux depending upon the needs of the measurement. The longer wavelength of 2.541 Å has ~5% λ/3 contamination and is mainly used for polarized neutron diffraction (S-bender will filter out the high-order contamination). The 1.546 Å-wavelength has the highest flux but with ~1.4% λ/2 contamination (PG filter is available to reduce the contamination below 10^-3), is mainly used for determining magnetic structures. The 1.005 Å wavelength is monochromatic and is good for precisely determining both nuclear and magnetic structures although the flux is 8 times lower than the highest flux at 1.546 Å.
Applications
The HB-3A DEMAND has the mission to explore nuclear and magnetic structures as a function of temperature, pressure, magnetic field, and electric field. The instrument is particularly suitable for studying phase transitions and accompanying structure changes, as well as measuring order parameters and exploring the phase diagram. It is also suitable for a wide range of small-unit-cell crystallography studies, including superlattice structures and atomic anharmonicity. Users have researched problems in physics, materials science, chemistry, and mineralogy. Recent specific areas of study include magnetic structure and nuclear superstructure in iron pnictide superconductors, magnetic and nuclear structures of possible quantum magnets, Weyl semimetals, topological insulators, multiferroic oxide phase transitions and diagrams, magnetic/orbital frustration in spinels, new permanent magnets, temperature dependence of atomic displacement parameters in battery and thermoelectric materials, structural phase transitions of photo-voltaic hybrid perovskites, hydrogen bonding in rock-forming minerals, crystallography of novel scintillators, and diffuse scattering.
These materials have a wide range of contemporary and prospective applications, such as terahertz equipment, sensors, high temperature power harvesting, high-efficient power transmission, green refrigeration, wireless communication, bolometers in space investigation, data storage and “qubit” in quantum computation.
Specifications
| Beam Spectrum | Thermal |
| Monochromators | Double focusing silicon |
| Monochromator angle | 47.5° |
| Incident Wavelengths | 1.005 Å (331), 1.546 Å (220), 2.541 Å (111) |
| Four-circle mode | Huber, half full χ circle, with 4 – 800 K CCR, 2Θ<95° |
| Two-axis mode | -181°< omega <181°, out-of-scattering plane coverage -8°< γ < 40°, 2Θ < 95° |
| Detector | 2D Anger camera |
| Crystal size requirement | > 0.1 mm3, maximum crystal dimension 5mm |
| Flux at sample | 2.2 × 107 n/cm2/s |
| Polarized neutron diffraction | Polarizer: In situ pumped 3He filter S-bender supermirror |
DEMAND Instrument Team
Please select link below to email the instrument team. Be sure to include your name and email address.
Contact the DEMAND Instrument Team
Emily Kroll – Scientific Associate
Yan Wu – Neutron Instrument Scientist
Yiqing Hao – Neutron Scattering Scientist
Strong D.; Hao Y.; Cao H.B.; Clements E.M.; Cava R.J.; May A.F. “Physical properties and anisotropic magnetism of EuBi2”, Journal of Magnetism and Magnetic Materials, 655, 174380, 2026
Ferrenti A.M.; Siegler M.A.; Hao Y.; Lygouras C.J.; Chen T.; Soetojo T.A.; Rutherford M.; Drichko N.; Cao H.B.; Kojima K.M.; Hallas A.M.; McQueen T.M. “K2Co2(TeO3)3 2.5H2O: A zemannite-type dimer antiferromagnet”, Physical Review Materials, 10, 094410, 2026
Li X.; Ren G.; Lu H.; Samanta K.; Shah A.K.; Huang K.; Omprakash P.; Yun Y.; Buragohain P.; Cao H.B.; Wu Y.; Hachtel J.; Lupini A.R.; Chi M.; Idrobo J.C.; Tsymbal E.Y.; Gruverman A.; Mishra R.; Xu X. “Antiferroelectric hafnia down to the 2D limit”, Science, 2026
Rehfuss Z.; Gould S.; Blawat J.; Broyles C.; Xu Q.; Hao Y.; Cao H.B.; Dinh T.; Xu S.Y.; Graf D.; Singleton J.; Ran S. “Field-rigid Ising antiferromagnetism with giant metamagnetic transition fields in van der Waals UOTe”, Physical Review B, 114, 144422, 2026
Denoel F.; Thilakan K.K.; Huang Y.C.; Shiino T.; Gebresenbut G.H.; Cao H.B.; Haussermann U.; Gomez C.P.; Sahlberg M.; Mathieu R. “Long-ranged spin-glass phase boundary in quasicrystal approximants”, Physical Review B, 114, 084404, 2026
Ma Q.; Billingsley B.R.; Niraula A.; Marshall M.; Dahlbom D.; Hao Y.; Pajerowski D.M.; Kolesnikov A.I.; Bai X.; Batista C.D.; Kong T.; Cao H.B. “Quantum Entanglement of XY-Type Spin Dimers on the Shastry-Sutherland Lattice”, Physical Review Letters, 137, 086701, 2026
Coles J.; McCray A.R.; Fichera B.T.; Wu Y.; Hao Y.; Phelan D.; Cao Y.; Osborn R.; Phatak C.M.; Rosenkranz S.; Li Y.; Li Y. “Model-free detection of physical order from scattering and imaging data using escort-weighted Shannon entropy and divergence matrices”, Physical Review Research, 8, 033235, 2026
Xia H.; Liu Z.; Wu Y.; Sun Q.; Hayashi N.; Shen X.; Cao H.B.; dela Cruz C.; Yu R.; Yang Y.f.; Takano M.; Long Y.W. “Small Co-doping induced magnetic and electrical transitions in single crystal CaFe0.95Co0.05O3”, Physical Review B, 113, 214443, 2026
Information for DEMAND Users
DEMAND runs with a large high-pixelated detector, that enables the efficient reciprocal space mapping, allowing the studying the novel structure and magnetic phases, and short-range order, even diffuse scattering. The instrument can run in the “Four-Circle mode” and “Two-axis mode” with easily switchable polarized and unpolarized neutron beam. The “Four-Circle mode” allows the full reciprocal space access, multiple scattering studies, high-resolution mapping the peak shape in 3D that can be used for detailed crystal screening, high pressure sciences, polarized neutron diffraction, electric field and stimulation, and other user-designed sample environment within the temperature range of 4 K-700 K. The “Two-Axis mode” is mostly for the experiments require the ultra-low temperature sample environment (0.04 K to 4 K) or/and cryomagnetic field (-6 to 6 T), in which, the large vertical detector coverage (-8o to 40o) ensures enough reciprocal space coverage out-of-scattering-plane. The polarized beam is available for both thermal neutrons of 1.5424 Å and cold neutrons of 1.541 Å with He-3 filter polarizer and S-bender supermirror polarizer, respectively. Two ways of data reduction are available, MantidWorkbench through https://analysis.sns.gov/ and ReTIA (Real-Time Image Analyzer).
Published articles present details the instrument’s capability and specification:
- B. C. Chakoumakos, et al., “Four-circle single-crystal neutron diffractometer at the High Flux Isotope Reactor“, Journal of Applied Crystallography 44, 655-658 (2011).
- H.B. Cao, et al., “DEMAND, a Dimensional Extreme Magnetic Neutron Diffractometer at the High Flux Isotope Reactor“, Crystals, 9, 1, 5 (2019).
- Y. Hao, et al., “Machine-learning-assisted automation of single-crystal neutron diffraction”, Journal of Applied Crystallography 56, 519-525 (2023).
For remote user experiments, please visit the User Guide to Remote Experiments webpage.
Shipping Addresses for Samples
For details information, please visit the ORNL User Facilities Sample Handling and Shipping page.
Non-activated samples coming to HFIR:
Recipient: IPTS XXXXX, HFIR user sample
Oak Ridge National Laboratory / HFIR Site
1 Bethel Valley Road
Bldg 7972 Room 100 [Special requirements (example: freezer or intert gas)]
Oak Ridge, TN 37830
HFIR Sample Management Desk phone number: 865-576-9030
Activated samples coming to HFIR:
Recipient: IPTS XXXXX, HFIR user sample [Replace the XXXX with your IPTS number]
Oak Ridge National Laboratory / HFIR Site
1 Bethel Valley Road
Bldg 7001 [Special requirements (example: freezer or intert gas)]
Oak Ridge, TN 37830
HFIR Sample Management Desk phone number: 865-576-9030
Users are encouraged to use a shipping provider who delivers directly to ORNL (ex: FedEx, UPS, DHL). These shipments are considered priorities and are processed through ORNL shipping facilities within 8-24 hours of delivery. Please be aware that the use of USPS may delay the processing of your shipment. due to a longer lead time for sorting.
NOTE: Replace the XXXX with your Integrated Proposal Tracking System (IPTS) number.
Software Downloads
Data is accessed and reduced remotely on the SNS analysis cluster using Mantidworkbench. A good tool to obtain an overview of your measured files is through ONCat.
The data reduction process has changed in 2021. Please refer to the following manuals for data reduction:
- MantidWorkbench – Data plotting and reduction software at analysis server. The manual explains how to login to the SNS analysis cluster, access data at Oncat and start data processing and visualizing data with MantidWorkbench (Example of Mantid scripts could be found at analysis cluster in /HFIR/HB3A/shared/Scripts/ : HB3A_visualization.py and HB3A_peakintegration.py).
- FullProf, Jana, and Shelx are the major refinement packages for determination of nuclear and magnetic structures.
- Bilbao Crystallographic Server and SaraH – contains the user friendly structural and magnetic symmetry analysis tools.
- ReTIA – Automated data reduction build in the instrument (in development). The manual is a quick guide for getting started on this software. .
- Graffiti – This program is an old version of data reduction software that allows the user to browse through the scans (.dat files) in the experiment. Data transfer with Graffiti is discontinued. But if the data has been downloaded to local PC and data path set as ***\HB3A\exp**\Datafiles, it could be used for quick checks on the data status.
Lecture Notes and Example Data
Please refer to the Lecture Notes page from the Magnetic Structure Determination from Neutron Diffraction Data Workshop 2016 for example data and relevant articles.
Capabilities of the DEMAND Instrument
The scientific communities that use the HB-3A instrument include condensed matter physics, chemistry, mineralogy, and materials science. Crystal and magnetic structure studies on single crystals are the instrument’s focused mission. DEMAND can efficiently map the full reciprocal space, is optimized for studying novel materials and complex magnetism, but is also capable of studying short range order and defect correlation. The sample environment covers 4-700 K with the closed-cycle refrigerator (CCR) at its Four-Circle mode, ultra-low temperature (0.04-4 K), and temperature beyond 700 K in its Two-Axis mode. Polarized beam can be switched on easily to measure weak ferromagnetism, magnetization density map, local site magnetic susceptivity.
Four-Circle mode: structure, site-disorder, magnetic orders, ordering parameters, determining propagation vectors, fitting magnetic scattering data to determine spin arrangement and moments. With a dedicated closed-cycle refrigerator mounted on the diffractometer, magnetic structural studies can be undertaken over the temperature range of 4 to 700 K.
Two-axis mode: magnetic orders, ordering parameters, determining propagation vectors, fitting magnetic scattering data to determine spin arrangement and moments, magnetic field dependence. With the cryomagnet (Mag-I) up to 6 T from 1.5 K to 10 K.
DEMAND Sample Environment
A list of equipment available at DEMAND can be found in the Sample Environment Equipment Database. The database contains detailed equipment specifications and images, drawings and other documents when available.
| Temperature (Cryostats) | 1.7 K to 300 K |
| Temperature (Closed Cycle Refrigerator) | 4 K to 700 K |
| Temperature (Ultra-Low temperature device) | Down to 0.05 K |
| Magnetic field | Up to 6 T vertical field |
| Pressure | Up to 1.8 GPa with clamp cell, Up to 10 GPa with other cells described below. |
| Electric field | Up to 10000 V/cm |
Closed Cycle Refrigerators—Bottom Loader
Typically used for single crystal experiments with four-circle mode, the bottom loading CCR has an operating temperature range of 3.6 K – 700 K (base/highest temperature dependent on particular CCR used). The standard sample is mounted in a single crystal sample can that has been vacuum sealed with an indium gasket in an inert atmosphere—for high temperature experiments, the indium gasket is omitted. The distance between the sample mount to beam center is a 2.375” (60 mm). Cooling to base takes approximately 2 hrs. High temperature bottom loading CCRs can reach temperatures up to 700 K and have a ¼-28 female interface and a 2.375” (60.3 mm) distance from the sample mount to beam center. Contact the DEMAND instrument team for more information.
Liquid Helium Cryostats—ILL Orange Cryofurnace and Oxford Variox
The top loading liquid helium cryostats have a base temperature of 1.5 K and can be used with ultra-low temperature inserts described below. The setup of DEMAND is two-axis mode. Cooling to base takes approximately 1.5 hrs. The same sample cans as used for the Janis CCR are used for the liquid helium cryostats. The sample mounts on the same ¼-28 female interface. The distance from the mounting interface to beam center varies from 1.75” (44.5 mm) to 2.44” (62 mm). The standard bore diameter is 1.9” (50 mm), however 2.75” (70 mm) and 3.937” (100 mm) diameter bores are available on the Orange cryostat for use with ultra-low temperature inserts. For concerns regarding sample mounting, contact the DEMAND instrument team.
How to change a sample in an ILL Orange Cryostat: SampleChangeforOrangeCryostat.pdf
Cryomagnets
Two vertical field cryomagnets are available for use on DEMAND, mag-I and Mag-J. Both Mag-I and Mag-J has a maximum vertical field of 6 T and have an operating temperature range of 1.5 K – 300 K. Contact the DEMAND instrument team for experiment planning.
How to change a sample in Mag-B: Operations for Sample Change in a Dynamic CTI QSG.pdf
Ultra-Low Temperature Inserts—Dilution Refrigerator and 3He
Two types of ultra-low temperature inserts are available for use with the Orange and Variox liquid helium cryostats as well as the cryomagnet. The Oxford Dilution insert reaches a base temperature of 0.03 K and the 3He insert of 0.3 K.
Pressure Cells
A 6 kbar Al-helium gas pressure cell is available for use in an Orange cryostat for in situ pressure changes. Various piston-cylinder clamped CuBe/ NiCrAl pressure cells (up to 2 GPa) are available for higher pressure experiments. Up to 10 GPa pressure with DAC has been commissioned at DEMAND. Other type of pressure cells working at difference pressure range could be accommodated at DEMAND. Please contact the DEMAND instrument team for planning neutron pressure experiments.
Additional Sample Environments
Additional custom specialized sample environments may be accommodated at the DEMAND—e.g. electric field, current tuning, etc. Users are strongly encouraged to discuss experimental needs with the DEMAND instrument team before requesting custom sample environments for their proposals.
Sample Holders
Various sample holders are available for single crystal sample mounting with custom mounts provided as needed. Users are strongly encouraged to discuss experimental needs with the DEMAND instrument team.
DEMAND Highlights
Ultralow Sample Temperatures available at HFIR HB-3A Single-Crystal Diffractometer
Temporary removal of the chi/phi axes allows room for an orange cryostat with He-3 insert, making use of the new overhead jib crane.
View the full presentation.
Cryostat at HB3A DEMAND Diffractometer
The cryostat has been tested at HB3A FCD and the data collected by the current 5x5cm Anger camera at 1.5 K were well fitted and consistent with the structure measured at 4 K with the regular CCR.
View the full presentation.
Initial test of the Diamond Anvil Cell (DAC) at HFIR HB-3A
With an optimized region of interest, the background is ~ 10 cts/s. The data will be used to judge the feasibility of a future DAC experiment.
View the full presentation.
Circular-magnetic k-vector observed on a 0.02 mm3 crystal at HFIR HB-3A
The circular distribution of k-vectors definitively confirms Fe3PO7 to have a “partially ordered” antiferromagnetic (AFM) helical state. One candidate for such a state is a short-range ordered AFM Skyrmion phase.
View the full presentation.
Orbital selective Mott transition observed in a quasi-1D Fe-based superconductor
Neutron diffraction has revealed that two iron based ladder compounds, CsFe2Se3 and BaFe2S3, exhibit highly contrasting responses to hydraulic pressure despite their identical crystal structure and similar magnetic structures. The magnetic order in CsFe2Se3 stays unchanged up to 2 GPa, while that in BaFe2S3 undergoes a rather abrupt enhancement around 1 GPa both in transition temperature and ordered moment. Such unusual change bear the signature of an orbital-selective Mott transition.
View the full presentation.
New magnetoelectric mechanism in a chiral-lattice antiferromagnet
Neutron scattering has shown that the spin-texture chirality in the chiral-lattice antiferromagnet MnSb2O6 is preserved when the electric polarization is reversed by the application of an external magnetic field.
View the full presentation.
A New Direction for Iron-Based Superconductors
Single-crystal neutron diffraction is a powerful means of determining magnetic structures, and here it is used to show the parent phase of superconductors in the KxFe2-ySe2 family has a novel magnetically ordered semiconducting ground state.
View the full presentation.
Controlling Magnetic Order by Chemical Compression
Magnetic properties of Ca1–xEuxCo2As2 vary from itinerant (3d) antiferromagnetism of Co in CaCo2As2 to the combination of itinerant (3d, Co) and localized (4f, Eu) ferromagnetism in the intermediate range to localized (4f) antiferromagnetism in Eu-rich samples.
View the full presentation.
Localized to Strongly Correlated Electron Transition in EuCo2As2
A combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.
View the full presentation.
Candidate Elastic Quantum Critical Point in LaCu6-xAux
A combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.
View the full presentation.
Spin Reorientation in TlFe1.6Se2 with Complete Vacancy Ordering
A combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.
View the full presentation.
Spin Reorientation and Magnetism in Yb14-xPrxMnSb11
An abnormal peak is observed in the dc magnetic susceptibility of Yb13.47Pr0.53MnSb11. Neutron diffraction clearly indicates that this peak is caused by a spin re-orientation of Mn moments, which is consistent with results of magnetization measurements. Refinement on the data collection also shows that moments on Mn are ordered and that moments on Pr are not.
View the full presentation.
Polarized Neutron Diffraction at HFIR HB-3A
High neutron polarization ratio (>94%) and a good transmission (16% based on the diffraction on a 2 mm size hexaferrite crystal) enable effective polarized neutron diffraction at HB-3A. Tolerance to the horizontal focus yields double the neutron flux. 24% transmission can be achieved by moving the polarizer closer to the sample position, which requires redesigning a more compact flipper and collimator mount.
View the full presentation.
Weak Itinerant Ferromagnetism Detected by Polarized Neutron Diffraction
High neutron polarization ratio (>95%) has been achieved at the HFIR HB-3A single crystal neutron diffractometer. This is the first use of this capability on an experiment approved through the General User program. We succeeded in detecting a weak itinerant ferromagnetic moment of 0.11(1)μB/atom on a NiCoCr0.6 crystal with an effective mass of 20 mg.
View the full presentation.
The ordered low-dimensional frustrated magnets challenge the nonlinear spin-wave theories
Results on an ordered low dimensional frustrated magnet suggest a new theoretical framework is needed for adequate description.
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SPICE upgrade for HB-3A 2D detector
Added cursors to identify each pixel ID, corresponding hkl, and received neutron counts. New function to let users define Region of Interests. Instrument configuration is written in each measured data. Improved capability for optimizing the data collections. Monitor was better synchronized through HFIRLITE
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Itinerant Antiferromagnetism in RuO2
Rutile-type RuO2 had been considered a Pauli paramagnet, until this report demonstrated a previously undetected lattice distortion below approximately 900 K accompanied by antiferromagnetic order. The room temperature magnetic moment of approximately 0.05 μB is small, but clearly confirmed by polarized neutron diffraction. This experiment and corresponding theory suggest that the combination of high Néel temperature and small itinerant moments in RuO2 are unique among metallic oxides.
View the full presentation.
DEMAND Spec Sheet
DEMAND Status
SPICE status: https://neutron.ornl.gov/hb3a/
Live Instrument data: https://monitor.sns.gov/dasmon/hb3a/
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