How to observe magnetic domains?

Magnetic domain observation methods can be roughly divided into the following three types:

1) Scanning Electron Microscope (SEM)

2) Scanning Probe Microscopy (SPM)

3) Magneto-optical Kerr effect microscope

The method using SEM includes observing the magnetic domain pattern obtained by attaching magnetic fine particles and colloidal particles to the surface of the sample under the application of a magnetic field, and the interaction between the electron beam and the sample in the SEM depends on the spin nature. There is a spin-polarized electron microscope (SP-SEM), which relies on it to visualize the magnetic information of a sample by using a.

SPM-based methods include: spin-polarized tunneling microscopy (SP-STM), which exploits the tunneling effect of spin-polarized electrons using conductive short arms; and magnetic force microscopy, which exploits the magnetic force of the short arms to detect the presence of Stray magnetic fields.

The method of magneto-optical Kerr effect (MOKE) microscopy is used to apply light to a magnetic body and change the rotation angle of the plane of polarization of the light according to the magnetization of the magnetic body.

Magnetic Domain Structure Observed by Kerr Microscopy，Size is 10-20 microns

The resolution of these methods is approximately SP-STM (<1 nm), SP-SEM (max 5 nm), SEM (max 10 nm), MFM (20-50 nm) and MOKE microscopy (max 1000 nm). And use according to the size of the magnetic domain. Among them, SP-STM, SP-SEM, MFM (20 to 50 nm) and MOKE microscope can observe the direction of the magnetization vector.

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