Laboratory of magneto-optical Kerr microscopy
Measuring method:
Magneto-optical Kerr microscopy for observation of magnetic domains at surfaces of materials, domains are investigated at room temperature in static magnetic field.
Laboratory equipment:
Optical microscope Zeiss, Xe lamp, optical components (polarizer, analyzer, lens, filters), objectives with different magnifications, CCD camera Hamamatsu, magnets generating magnetic field in the sample plane and perpendicular to the sample plane, power supply Kepco, software Kerrlab, antivibration table, CMOS camera, two indicator garnet films on transparent substrate with mirror at the backside (magneto-optical indicator films).
Investigated materials:
Solid ferromagnetic and ferrimagnetic materials (low surface roughness is necessary) – thin films, multilayers, amorphous and nanocrystalline materials based on Fe, Co and Ni.
Investigated properties of materials:
- visualization of surface magnetic domains and states of magnetization using the polar, longitudinal and transversal Kerr effect
- possibility to observe magnetic domains in local areas due to focusing of beam into the different places on the sample surface
- measurements of magneto-optical hysteresis loops from changes of optical contrast on the sample surface in varying magnetic field
- observation of magnetic domains at rough surfaces using the method of magneto-optical indicator film (MOIF)
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Tab. 1 Objectives EC Epiplan-Neofluar Pol and their parameters
| Objective magnification x/numerical aperture | Size of viewing field [mm] | Ideal resolution [nm] |
|---|---|---|
| 2,5x/0,06 | 3,600 x 2,720 | 6100 |
| 10x/0,25 | 0,900 x 0,680 | 1464 |
| 20x/0,50 | 0,450 x 0,340 | 732 |
| 50x/0,80 | 0,180 x 0,136 | 457 |
| 100x/0,90 | 0,090 x 0,068 | 406 |
Tab. 2 Used magnets
| Magnetic field generated along the sample surface | ||
|---|---|---|
| Air coil, gap distance 38 mm | Hmax = 32 kA/m | I = 4 A |
| Poles for lower field poles gap 25 mm | Hmax = 280 kA/m | |
| Poles for higher field poles gap 12,5 mm | Hmax = 480 kA/m | |
| Magnetic field generated perpendicularly to the sample surface | ||
| Cylindrically symmetric magnet | Hmax = 288 kA/m | I = 4 A |
Laboratory of magneto-optical Kerr microscopy