High-Field Diffractometer

Instrument for Dichroic Soft X-ray Absorption and Scattering Experiments in High Magnetic Fields

The High-Field Diffractometer is dedicated to both soft-x-ray absorption (XAS) and resonant soft x-ray scattering (RSXS) in magnetic fields up to 7 Tesla and temperatures down to 4 K. This combination of high magnetic fields and low temperatures renders the setup ideal for studying weakly coupled magnetic systems like diluted magnets or single molecular magnets. The unique feature of this instrument is an in-vacuum superconducting coil that can be rotated independently from the sample. It is therefore perfectly suited for XMCD and XMLD experiments in various geometries.

Anwendungsbeispiele:

Diffraction from complex electronic superstructures (magnetic, charge and orbital order)
Magnetization states of single molecular magnets
Element-specific magnetic hysteresis loops (switching behavior in heterostructures or alloys, exchange bias)
Electronic ground states in crystals

Magnet angles and slits to estimate possible x-ray scattering geometries (courtesy A. Frano).

Methods

XMLD, XMCD, REXS, Magnetic Scattering

Remote access

depends on experiment - please discuss with Instrument Scientist

Beamline data
Energy range	120 - 2000 eV
Energy resolution	10 000
Flux	10¹²
Polarisation	linear any angle (with restrictions) circular
Focus size (hor. x vert.)	focussed beam: typically 100 µm x 50 µm ultimate 40 µm x 10 µm collimated beam: ≤ 1.7 mm x 1.5 mm (depending on apertures)
Phone	+49 30 8062 14717
Weitere Details	UE46_PGM-1
Station data
Temperature range	4 - 350 K
Pressure range	< 10^-10 mbar
Detector	AXUV100 type photodiode
Manipulators	x/y/z
Sample holder compatibility	Scattering Geometry: horizontal Sample rotation: limited, depending on orientation of the magnet Software: SPEC Native sample holders Omicron sample plates
Additional equipment	Magnetic Field: 7 Tesla Magnetic Field Geometry: horizontal, rotatable (90 deg.) with respect to sample Pulsed magnetic fields up to 30 Tesla becoming available for selected experiments, please contact Instrument Scientists

The High-Field Diffractometer is an endstation for both soft-x-ray absorption (XAS) and resonant soft x-ray scattering (RSXS) in magnetic fields up to 7 Tesla and temperatures down to 4 K. This combination of high magnetic fields and low temperatures renders the setup ideal for studying weakly coupled magnetic systems like diluted magnets or single molecular magnets. The unique feature of this endstation is an in-vacuum superconducting coil that can be rotated independently from the sample. The station is therefore perfectly suited for XMCD and XMLD experiments in various geometries. The absorption signal is typically measured in the TEY-mode via the sample drain current. Employing continuous mode, a pair of energy-dependent absorption scans with opposite light helicities can be recorded with very high quality within less than 10 minutes. Depending on the sample, noise ratios as low as 10^-4 can be achieved. A rotatable photon detector enables to perform dichroism experiments using specular reflectivity, which is often more sensitive to tiny magnetizations at interfaces and less surface sensitive than TEY-mode experiments. The same detector permits RSXS experiments at relevant scattering geometries to study the evolution of electronic ordering phenomena, like charge and orbital ordering in high magnetic fields, being at the heart of many of todays most fascinating macroscopic phenomena in complex oxides. Samples are transferred in a fast and reliable way from outside vacuum to a sample holder directly attached to a LHe-flow cryostat that provides the base temperatures of 4 K. The endstation is permanently attached to the UE46_PGM1 beamline providing high photon flux between 120eV and 2000 eV and variable photon polarization. The beamline also hosts the XUV Diffractometer, an instrument dedicated to high performance RSXS studies. Both instruments can be used within the same beam time. Beamline and instruments are operated by the Institute Quantum Phenomena in Novel Materials at HZB.