The magneto-optical Kerr effect (MOKE) is used to capture variations in magnetic permeability and magnetization to determine the presence of sensitization. MOKE-magnetometry-based systems and apparatus may be used to provide in-field magnetic measurements, and may be particularly useful in methods for assessing changes in composition, crystal structure, and grain size in magnetic materials.

An apparatus comprises a spindle to rotate a magnetic recording medium and a magnetic field generator to expose a track of the medium to a DC magnetic field. The magnetic field generator is configured to saturate the track during an erase mode and reverse the DC magnetic field impinging the track during a writing mode. A laser arrangement heats the track during the erase mode and, during the writing mode, heats the track while the track is exposed to the reversed DC magnetic field so as to write a magnetic pattern thereon. A reader reads the magnetic pattern and generates a read signal. A processor is coupled to the reader and configured to determine an anisotropy parameter using the read signal. The apparatus can further comprise a Kerr sensor that generates a Kerr signal using the magnetic pattern.

An inspection device includes a light source, an MO crystal disposed to face a semiconductor device (D), an object lens configured to concentrate the light output from the light source onto the MO crystal, a holder configured to hold the MO crystal, a flexible member interposed between the MO crystal and the holder, and an object lens drive unit configured to cause the MO crystal to contact the semiconductor device (D) by causing the holder to be moved in the optical axis direction of the object lens, wherein, when the MO crystal contacts the semiconductor device (D), the flexible member is bent, so that an incident plane is inclined in a range in which an inclination angle of the incident plane of the light in the MO crystal with respect to a plane orthogonal to the optical axis is less than or equal to an aperture angle.

An apparatus comprises a spindle to rotate a magnetic recording medium and a magnetic field generator to expose a track of the medium to a DC magnetic field. The magnetic field generator is configured to saturate the track during an erase mode and reverse the DC magnetic field impinging the track during a writing mode. A laser arrangement heats the track during the erase mode and, during the writing mode, heats the track while the track is exposed to the reversed DC magnetic field so as to write a magnetic pattern thereon. A reader reads the magnetic pattern and generates a read signal. A processor is coupled to the reader and configured to measure one or more magnetic properties of the track using the read signal. The apparatus can further comprise a Kerr sensor that generates a Kerr signal using the magnetic pattern.

An inspection device improves accuracy characteristics of an (MRAM), the inspection device including a stage on which a MRAM element is fixed, and electromagnets generating a first magnetic field. A magnetic field having a component in a direction perpendicular to the stage is changeable from a first direction to a second direction according to a position on the stage. A second magnetic field in which a direction of a magnetic field component is parallel to the stage changes from a third direction to a fourth direction according to the position on the stage, an optical system illuminating the MRAM element with light including polarized light, and condensing reflected light from reflected illumination light from the MRAM element, and a detector detecting reflected light when the position of the MRAM element is changed, and when the position of the MRAM element in the second magnetic field is changed.

A spin-orbit torque (SOT) measuring apparatus includes a photoelastic modulator (PEM) configured to periodically modulate a polarization direction of linearly polarized incident light and emit a periodically modulated light, a first polarization rotator configured to rotate a polarization direction of the periodically modulated light, a voltage generator configured to generate an AC current to a sample to which light with the rotated polarization direction is to be emitted, a prism configured to split light reflected into first light and second light having different polarization directions, a balanced detector configured to output a signal corresponding to an intensity difference between the first light and the second light, a changing circuit configured to change a frequency component to the intensity difference, and an amplitude measurer configured to measure an amplitude of a frequency component corresponding to a modulation frequency of the PEM with the changed frequency component.

A spin-orbit torque (SOT) measuring apparatus includes a photoelastic modulator (PEM) configured to periodically modulate a polarization direction of linearly polarized incident light and emit a periodically modulated light, a first polarization rotator configured to rotate a polarization direction of the periodically modulated light, a voltage generator configured to generate an AC current to a sample to which light with the rotated polarization direction is to be emitted, a prism configured to split light reflected into first light and second light having different polarization directions, a balanced detector configured to output a signal corresponding to an intensity difference between the first light and the second light, a changing circuit configured to change a frequency component to the intensity difference, and an amplitude measurer configured to measure an amplitude of a frequency component corresponding to a modulation frequency of the PEM with the changed frequency component.