System for measuring linear and non-linear magneto-optical Kerr rotation

Abstract

The invention discloses a system for measuring linear and non-linear magneto-optical Kerr rotation, which comprises an ultra-short pulse laser, a helium-based closed-cycle refrigerator, an electromagnet, a laser-pumping optical path, a laser-detection optical path, a linear Kerr signal collection optical path, a non-linear Kerr signal collection optical path, a lock-in amplifier signal collection system and a laser spot monitoring system, wherein the helium-based closed-cycle refrigerator is provided with optical windows and used for controlling the temperature of a sample; the size of the air gap and the magnitude of the magnetic field of the electromagnet are adjustable; the laser-pumping optical path is used for leading in the laser inputted by the ultra-short pulse laser and focusing the laser on the surface of the sample inside the refrigerating head, so as to excite the sample; the polarization plane of the laser-detection optical path rotates after a beam of laser outputted by the ultra-short pulse laser is reflected by the sample; the linear Kerr signal collection optical path is used for collecting the base-frequency signal of the detection laser; the non-linear Kerr signal collection optical path is used for receiving the frequency-doubled signal of the detection laser; the lock-in amplifier signal collection system is used for filtering and amplifying the signals and transmitting the signals to a computer for processing; and the laser spot monitoring system is used for accurately controlling the overlap ratio of the pumped beam laser spot and the detected beam laser sport. The system provided by the invention for measuring the linear and non-linear magneto-optical Kerr rotation is capable of simultaneously adjusting the temperature and the intensity of the magnetic field applied to the sample and achieving the measurement of the linear and non-linear magneto-optical Kerr effect on a temperature-variable steady-state basis or a time-resolved dynamic basis.

Description

Technical field [0001] The invention relates to a time-resolved linear and nonlinear magneto-optical Kerr measurement system for measuring magnetic metals, semi-metals, semiconductor film materials and low-dimensional quantum structures. Background technique [0002] Semiconductor spintronics has received extensive attention because of its advantages that conventional electronics can’t match. The study of spin polarization and its dynamic evolution is an important part of the basic physics research of spintronics. The experimental research on this problem is mainly realized by time-resolved magneto-optical Kerr rotation technology. The principle is: a beam of linearly polarized laser is incident on the material under study. The magneto-optical effect occurs due to the interaction of the photon and the electron spin magnetic moment of the material, that is, the refractive index of the material changes, resulting in the polarization plane of the reflected laser. Rotate, the rotat...

AI Technical Summary

Problems solved by technology

Usually, the samples are placed on the sample holder, and then they are immersed in the liquid helium Dewar for measurement, so it is difficult to continuously change the test temperature of the sample and the size of the magnetic field

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