a) Schematic diagram of experimental setup. The Cu piece and the ferromagnetic metal sample were connected by ultrasonic welding. b) The relationship between the respective lateral photovoltaic voltage and the measuring electrode spacing of the magnetic metal and Si. The symbol is experimental data, and the solid line is the theoretical calculation result. The laser power is 30mW and the wavelength is 650nm.
Magnetoelectronics has great potential in a new generation of information technology and has always been a focus of international attention. The work can be divided into two aspects. One is the use of spin Hall effect, spin Seebeck effect and electron tunneling effect to generate and manipulate spin currents. There has been a lot of work in this area. Another important development trend is the use of magnetic fields to regulate the trajectories of electrons in semiconductors: By directing magnetic fields to semiconductors, the Lorentz effect is used to deflect electron orbits, and magnetic behaviors of electronic behaviors are obtained.
However, because conventional semiconductors are insensitive to magnetic fields, the required magnetic field is usually high, which is several or even more than a dozen Tesla. Various efforts have been made, such as designing sample structures and exploring new regulatory mechanisms to increase the magnetic field sensitivity of semiconductors, but the effects are not ideal. Therefore, exploring the principles of magnetic regulation of new semiconductors remains an issue of great concern internationally.
Recently, the Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics (National Science Laboratory for Condensed Matter Physics), Sun Jirong's Ph.D. student Wang Qihu, etc., established a strong relationship between semiconductors and magnetic metals, through the regulation of magnetic fields. The sensitive magnetic metal realizes the low magnetic field regulation of the electronic motion inside the semiconductor, and the magnetic field producing a significant magnetic effect is only a few oersteds.
They found that the use of magnetic metals and semiconductors to form the Schottky junction, when photoexcitation of non-equilibrium carriers, the electrons in the semiconductor and magnetic metal holes through the interface barrier and Coulomb interaction to form electron-hole pairs . When the magnetic field affects the carrier of the magnetic metal, it simultaneously affects the diffusion behavior of the electrons in the semiconductor, and then a new type of magnetic effect is generated, resulting in the variation of the lateral photovoltaic voltage of the magnetic metal and the semiconductor with the magnetic field.
It was found that the transverse photovoltaic change in magnetic Fe-Mo alloy at 4 Oe is about 1%, which is close to the intrinsic anisotropic magnetoresistance of Permalloy; interestingly, the lateral photovoltaic effect with magnetic field is also observed on semiconductor Si. Change, and the relative change is much higher than Permalloy, up to 3.5%, thus achieving a low magnetic field control of Si in the electronic process.
Further, they identified the key factors affecting the magnetic field effect of semiconductors and provided theoretical guidance for the design and regulation of semiconductor magnetic field effects. In addition to the lateral photovoltaic effect, they also discovered for the first time the planar Hall effect formed by the diffusion of non-equilibrium carriers in the alloy. These efforts have opened up new research space for semiconductor magnetic control. This work was published in Advanced Materials [Adv. Mater. DOI: 10.1002/adma.201403868]. Related research has been supported by the National Natural Science Foundation of China, the Ministry of Science and Technology, and the relevant funds of the Chinese Academy of Sciences.
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