Institut des
NanoSciences de Paris
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Nanostructures and Quantum Systems

Variable temperature Kerr microscope

Contact :, Catherine Gourdon, Laura Thevenard

Polarization microscope in reflection to image magnetic domains by magneto-optical Kerr effect :

-  Sample cooled by contact on a pillar cryostat (Oxford Microstat BT HiRes II 4-300 K)
-  various light sources : filtered white lamp, LED, continuous laser (Ti-sapphire, Argon, He-Ne)
-  Intensified Andor Clara CCD detector, with the possibility to trigger image acquisition externally. It is also possible to do micro-spectroscopy experiment by sending part of the signal of the image to a spectrometer

- out-of-plane magnetic fields :

  • Electro-magnet going up to 60mT
  • Supra-conductive coil going up to 6T
  • Micro-coil mounted in the cryostat, on the cold finger, delivering up to 200mT with short pulses of rise time 140ns

- in-plane magnetic fields :

  • CAYLAR air-cooled rotating dipole going up to 500mT (Fig. 2b)
  • homemade solenoid going up to 50mT
  • home-made micro-coil mounted in the cryostat, on the cold finger, delivering up to 15 mT with short pulses of rise time 150ns (Fig. 2a)

Polar Kerr configuration

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(a) Polar Kerr microscope set-up (schematics by A. Dourlat). (b) Zero-field domain self-organisation in out-of-plane magnetized (Ga,Mn)(As,P) Haghgoo et al., PRB’10.

 

Longitudinal Kerr configuration

 

 

[click to enlarge] Fig. 2 : (a) Micro-coils inserted in the cryostat for short field pulses in the plane of the sample. The outer coils (in red) are for saturating at higher fields. (b) Domain-wall velocity measured on in-plane magnetized GaMnAsP Thevenard et al. PRB ’12. (c) CAYLAR rotating dipole.

[May 2016]