High-Field Diffractometer

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

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

Methods

XMLD, XMCD, REXS, Magnetic Scattering

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.

Selected Applications

• 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

Selected Publications

• Ellis, D.S.; Weschke, E.; Kay, A.; Grave, D.; Malviya, K.D.; Mor, H.; de Groot, F.M.; Dotan, H.; Rothschild, A.: Magnetic states at the surface of α-Fe₂O₃ thin films doped with Ti, Zn, or Sn. Physical Review B 96 (2017), p. 094426/1-7

• da Silva Neto, E.H.; Yu, B.; Minola, M.; Sutarto, R.; Schierle, E.; Boschini, F.; Zonno, M.; Bluschke, M.; Higgins, J.; Li, Y.; Yu, G.; Weschke, E.; He, F.; Le Tacon, M.; Greene, R.L.; Greven, M.; Sawatzky, G.A.; Keimer, B.; Damascelli, A.: Doping-dependent charge order correlations in electron-doped cuprates. Science Advances 2 (2016), p. e1600782/1-6

• Sánchez-Barriga, J.; Varykhalov, A.; Springholz, G.; Steiner, H.; Kirchschlager, R.; Bauer, G.; Caha, O.; Schierle, E.; Weschke, E.; Uenal, A. A.; Valencia, S.; Dunst, M.; Braun, J.; Ebert, H.; Minar, J.; Golias, E.; Yashina, L.V.; Ney, A.; Holy, V.; Rader, O.: Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi_1-xMn_x)₂Se₃. Nature Communications 7 (2016), p. 10559/1-10

• Grisolia, M. N.; Varignon, J.; Sanchez-Santolino, G.; Arora, A.; Valencia, S.; Varela, M.; Abrudan, R.; Weschke, E.; Schierle, E.; Rault, J. E.; Rueff, J. -P.; Barthelemy, A.; Santamaria, J.; Bibes, M.: Hybridization-controlled charge transfer and induced magnetism at correlated oxide interfaces. Nature Physics 12 (2016), p. 484-493

• Bernien, M.; Naggert, H.; Arruda, L.M.; Kipgen, L.; Nickel, F.; Miguel, J.; Hermanns, C.F.; Krüger, A.; Krüger, D.; Schierle, E.; Weschke, E.; Tuczek, F.; Kuch, W.: Highly Efficient Thermal and Light-Induced Spin-State Switching of an Fe(II) Complex in Direct Contact with a Solid Surface. ACS Nano 9 (2015), p. 8960-8966

• Matsuda, T.; Partzsch, S.; Tsuyama, T.; Schierle, E.; Weschke, E.; Geck, J.; Saito, T.; Ishiwata, S.; Tokura, Y.; Wadati, H.: Observation of a Devil's Staircase in the Novel Spin-Valve System SrCo₆O₁₁. Physical Review Letters 114 (2015), p. 236403/1-5

• Blanco-Canosa, S.; Frano, A.; Schierle, E.; Porras, J.; Loew, T.; Minola, M.; Bluschke, M.; Weschke, E.; Keimer, B.: Resonant x-ray scattering study of charge-density wave correlations in YBa₂Cu₃O_6+x. Physical Review B 90 (2014), p. 054513/1-13

• Schmitz-Antoniak, C.; Schmitz, D.; Borisov, P.; de Groot, F.M.F.; Stienen, S.; Warland, A.; Krumme, B.; Feyerherm, R.; Dudzik, E.; Kleemann, W.; Wende, H.: Electric in-plane polarisation in multiferroic CoFe₂O₄/BaTiO₃ nanocomposite tuned by magnetic fields. Nature Communications 4 (2013), p. 2051/1-8