Capabilities of the DEMAND Instrument

Dimensional Extreme Magnetic Neutron Diffractometer

DEMAND | HB-3A | HFIR

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.

Novel materials: structure and magnetism

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Reference:
Hu C., Ding L., Gordon K.N., Ghosh B., Tien H.J., Li H., Linn A.G., Lien S., Huang C., Mackey S., Liu J.Y., Reddy P.V., Singh B., Agarwal A., Bansil A., Song M., Li D., Xu S.Y., Lin H., Cao H.B., Chang T.R., Dessau D.S., Ni N., "Realization of an intrinsic ferromagnetic topological state in MnBi8Te13", Science Advances, 6, 30, eaba4275 (2020).

Ding L., Hu C., Ye F., Feng E., Ni N., Cao H.B., "Crystal and magnetic structures of magnetic topological insulators MnBi2Te4 and MnBi4Te7", Physical Review B, 101, 020412(R) (2020).

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.

Novel magnetism: Field-tunable toroidic orders

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Reference:
Ding L., Xu X., Jeschke H.O., Bai X., Feng E., Alemayehu A.S., Kim J.W., Huang F., Zhang Q., Ding X., Harrison N., Zapf V.S., Khomskii D., Mazin I.I., Cheong S.W., Cao H.B., "Field-tunable toroidal moment in a chiral-lattice magnet", Nature Communications, 12, 5339 (2021).

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.

Polarized neutron diffraction: Local Site Magnetic Susceptibility

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$Polarized neutron diffraction: Local Site Magnetic Susceptibility$

Reference:
Marshall M., Billingsley B.R., Bai X., Ma Q., Kong T., Cao H.B., "Field-induced partial disorder in a Shastry-Sutherland lattice", Nature Communications, 14, 3641 (2023).

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 at ultra-low temperature (40 mK to 10 K)

Polarized neutron diffraction: magnetization density map

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$Polarized neutron diffraction: magnetization density map$

Reference:
Ding L., Hu C., Feng E., Jiang C., Kibalin I.A., Gukasov A., Chi M., Ni N., Cao H.B., "Neutron diffraction study of magnetism in van der Waals layered MnBi2n Te3n+1", Journal of Physics D: Applied Physics, 54, 174003 (2021).

Nuclear structural symmetry

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Reference:
Du Q., Wu L., Cao H.B., Kang C., Nelson C., Pascut G., Besara T., Siegrist T., Haule K., Kotliar G., Zaliznyak I.A., Zhu Y., Petrovic C., "Vacancy defect control of colossal thermopower in FeSb2", npj Quantum Materials, 6, 13 (2021).

High-resolution crystallography

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Reference:
Cao H.B., Zhao Z.Y., Lee M., Choi E.S., McGuire M.A., Sales B.C., Zhou H.D., Yan J.Q., Mandrus D., "High pressure floating zone growth and structural properties of ferrimagnetic quantum paraelectric BaFe12O19", APL Materials, 3, 062512 (2015).

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Reference:
Li C.W., Ma J., Cao H.B., May A.F., Abernathy D.L., Ehlers G., Hoffmann C., Wang X.P., Hong T., Huq A., Gourdon O.A., Delaire O., "Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics", Physical Review B, 90, 214303 (2014).

H or light atom positions, phase transitions, ADP temperature dependence, nuclear density maps, thermal expansion mechanisms, etc. Positions and displacement parameters of light atoms can be particularly well determined compared to using x-ray diffraction. Intensity data are typically collected with omega scans in bisecting mode (omega ~ ½ 2-theta), and the horizontal angular divergence of the incident beam can be adjusted to maximize the scattered intensity.

Charge Density Waves and Structural Instability

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Reference:
Arachchige H.S., Meier W.R., Marshall M., Matsuoka T., Xue R., McGuire M.A., Hermann R.P., Cao H.B., Mandrus D., "Charge Density Wave in Kagome Lattice Intermetallic ScV6Sn6", Physical Review Letters, 129, 216402 (2022).

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Reference:
Cao H.B., Chakoumakos B. C., Chen X., Yan J., McGuire M. A.,Yang H., Custelcean R., Zhou H., Singh D. J., and Mandrus D., “Origin of the phase transition in IrTe2: Structural modulation and local bonding instability”, Phys. Rev. B 88, 115122 (2013)

Neutrons, X-rays, and electrons scattering together yield the high contrast for unraveling the cause of charge density wave order and bonding instabilities.

Structural phase transformations

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Reference:
Song Y., Cao H.B., Chakoumakos B.C., Zhao Y., Wang A., Lei H., Petrovic C., Birgeneau R.J., "Intertwined Magnetic and Nematic Orders in Semiconducting KFe0.8Ag1.2Te2", Physical Review Letters, 122, 8, 087201 (2019).

Symmetry changes, modulations, etc. The horizontal angular divergence of the incident neutron beam can be reduced by flattening the monochromator and thereby making the high resolution DQ/Q ~ 0.5%. This enables the resolution of small peak splittings due to symmetry changes.

Short-range order (i.e., diffuse scattering)

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Reference:
Dun Z.L., Daum M., Baral R., Fischer H.E., Cao H.B., Liu Y., Stone M.B., Rodriguez-Rivera J.A., Choi E.S., Huang Q., Zhou H.D., Mourigal M., Frandsen B.A., "Neutron scattering investigation of proposed Kosterlitz-Thouless transitions in the triangular-lattice Ising antiferromagnet TmMgGaO4", Physical Review B, 103, 064424 (2021).

short_range2.png

Reference:
Sarkis C.L., Tarne M., Neilson J.R., Cao H.B., Coldren E., Gelfand M.P., Ross K.A., "Partial antiferromagnetic helical order in single-crystal Fe3PO4O3", Physical Review B, 101, 184417 (2020).

Detailed mapping of magnetic or nuclear scattering in 1-D, 2-D, or 3-D grids. Reciprocal space scanning can be done along lines or grids. We are testing a 2-D detector that will make this more efficient.

Neutron Diffraction Manipulating High Pressure/ Electric Voltage/ Current

Uniaxial pressure

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Reference:
Chen T., Chen Y., Kreisel A., Lu X., Schneidewind A., Qiu Y., Park J.T., Perring T.G., Stewart J.R., Cao H.B., Zhang R., Li Y., Rong Y., Wei Y., Andersen B.M., Hirschfeld P.J., Broholm C., Dai P.C., "Anisotropic spin fluctuations in detwinned FeSe", Nature Materials, 18, 709-716 (2019).

Hydrostatic pressure CuBe pressure cell (0.5-2 GPa)

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Ref paper:
Chi S.X., Uwatoko Y., Cao H.B., Hirata Y., Hashizume K., Aoyama T., Ohgushi K., "Magnetic precursor of the pressure-induced superconductivity in Fe-ladder compounds", Physical Review Letters, 117, 4, 047003 (2016).

Hydrostatic pressure Diamond Anvil Cell DAC (1-10 GPa)

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Electric field (0-10kV/cm)

Ratcliff II W., Yamani Z., Anbusathaiah V., Gao T.R., Kienzle P.A., Cao H.B., Takeuchi I., "Electric-field-controlled antiferromagnetic domains in epitaxial BiFeO3 thin films probed by neutron diffraction", Physical Review B, 87, 140405 (2013).
Zou T., Dun Z.L., Cao H.B., Zhu M., Coulter D., Zhou H.D., Ke X., "Excess hole induced high temperature polarized state and its correlation with the multiferroicity in single crystalline DyMnO3", Applied Physics Letters, 105, 052906 (2014).
Zou T., Dun Z.L., Cao H.B., Zhu M., Zhou H.D., Ke X., "Tuning the ferroelectric state in multiferroic TbMnO3 single crystal by a trapped-charge-induced internal electric field", Journal of Applied Physics, 116, 10, 104101 (2014).

We try to widen the availability of high pressure/ electric voltage/ current high tuning measurement on DEMAND.

Thin film

Balasubramanian B., Zhao X., Valloppilly S.R., Beniwal S., Skomski R., Sarella A., Jin Y., Li X., Xu X., Cao H.B., Wang H., Enders A., Wang C.Z., Ho K.M., Sellmyer D.J., "Magnetism of new metastable cobalt-nitride compounds", Nanoscale, 10, 13011–13021 (2018).
Sinha K., Wang H., Wang X., Zhou L., Yin Y., Wang W., Cheng X.M., Keavney D.J., Cao H.B., Liu Y., Wu X., Xu X., "Tuning the Néel Temperature of Hexagonal Ferrites by Structural Distortion", Physical Review Letters, 121, 23, 237203 (2018).