Institut des
NanoSciences de Paris

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


(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]