Magneto-optic circular polarization dichroism measuring system capable of adjusting measuring geometry

Abstract

A measuring system for measuring the dichroism of the magneto-optical circular polarization with adjustable measuring geometry is provided, whose structure is that: a femtosecond laser excites the white light of the ultra-continuous spectrum, and divides the light by a monochrometer, which forms a monochromatic light whose wavelength can be adjustable. The monochromatic light can polarize through a purified Glan-Taylor prism with the extinction coefficient of 10 <5>; a lantern fly modulator, whose optical axis is 45degree angled with the optical axis of the Glan-Taylor prism to make the light become the circularly polarized light with the alternative variation of the sinistrality and the dextrorotation; a sample, which is put on the center of the cryogenic magnet; The circularly polarized light focuses on the sample, and the reflex reflected from the sample is focuses on the first LED detector; a phase-locking amplifier, whose reference signal is provided by the lantern fly modulator used for testing the difference of light intensity between the sinistrality and the dextrorotation of the circularly polarized light. The invention can not only test the frequency spectrum of the dichroism of the magneto-optical circular polarization of the materials, magnetic density and temperature dependence, but also can test the magnetocrystalline anisotropy of the magnetic semiconductor.

Description

technical field [0001] The invention belongs to the technical field of semiconductor optical property testing and magnetic material testing of magnetic materials, and in particular relates to the measurement technology of magnetic semiconductor magneto-optical spectrum, hysteresis loop, Curie temperature and magnetocrystalline anisotropy, and specifically relates to a Magneto-optic circular dichroism measurement system with adjustable measurement geometry Background technique [0002] Diluted magnetic semiconductors have both magnetic and semiconducting properties, and can be used in both information storage and information processing. Due to the existence of the Zeeman effect, the external magnetic field will cause the semiconductor energy band to split, and the split energy bands not only have different energies, but also have different spin orientations. At this time, the light absorption properties of the semiconductor will change accordingly. Not only wavelength select...

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Problems solved by technology

[0012] However, sensitive photomultiplier tubes can only work in a completely dark environment, which requires the entire test to be carried out in a closed darkroom system, and due to the large volume of photomultiplier tubes and poor compatibility with detection interfaces, currently reported The magneto-optic circular dichroism measurement system of our company adopts the measurement geometry that the light is close to the surface of the vertically incident sample, so the magnetization characteristics characterized by the magneto-optic circular dichroism are the perpendicular magnetization characteristics of the magnetic field perpendicular to the sample.

There is no doubt that the photomultiplier tube is used for measurement because the light intensity of ordinary halogen lamps is too weak, and it is difficult for ordinary light detectors to detect weaker light intensity changes

On the other hand, due to the large filament area of ​​the usual halogen lamp, the collimation of the light source is poor, and the light is difficult to focus, which limits the flexible change of the magneto-optic circular dichroism in the measurement geometry, resulting in almost No one has used magnetic circular dichroism to study the magnetocrystalline anisotropy of materials, which is a very important aspect in the study of magnetic materials

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