Applications & Highlights

Under construction

D7 is mainly used to measure diffuse scattering in single- and poly-crystalline samples using XYZ polarization analysis. Such diffuse scattering may be caused by short-range magnetic correlations and magnetic defect structures, or nuclear defect structures. Since the diffuse scattering is usually small, and is usually accompanied by other larger contributions to the total scattering, the use of polarization analysis to separate the magnetic and non-magnetic contributions is essential.

In addition, polarization analysis can be used to separate incoherent and coherent scattering contributions, and thus distinguish between single particle and cooperative excitations in non-magnetic systems.

Main applications :

Magnetic short range order in frustrated magnets and spin-glasses
Studies of non-collinear ferromagnetism
Extended magnetic defects in antiferromagnetic materials
Studies of hydrogen diffusion in metals
Separation of collective and single particle excitations in materials

Recent highlights :

Pinch Points in the Magnetic Coulomb Phase of Spin Ice

Under construction.

T. Fennell et. al. Science 326, 415 (2009)

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Short Range Correlations in the s = 1/2 Antiferromagnet Volborthite

Under construction

G. J. Nilsen et. al. Phys. Rev. B 84, 172401 (2011)

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Coexistence of Long and Short Range Order in SrEr2O4

Single crystal neutron diﬀraction reveals two distinct components to the magnetic ordering in geometrically frustrated SrEr₂O₄. One component is a long-range ordered k = 0 structure which appears below T_N= 0.75 K. Another component is a short-range incommensurate structure which manifests itself by the presence of a strong diﬀuse scattering signal. On cooling from higher temperatures down to 0.06 K, the partially ordered component does not undergo a pronounced phase transition. The magnetic moments in the long-range commensurate and short-range incommensurate structures are predominantly pointing along the [001] and [100] axes respectively. The unusual coexistence of two magnetic structures is probed using both unpolarised and XYZ-polarised neutron scattering techniques. The observed diﬀuse scattering pattern can be satisfactorily reproduced with a classical Monte Carlo simulation by using a simple model based on a ladder of triangles.

T. J. Hayes et. al. Phys. Rev. B 84, 174435 (2011)

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