Giant Magnetoresistance Effect Of 2EDG Under An Inhomogeneous Magnetic Modulation

Giant magnetoresistance(GMR)effect have attracted increasing attention since its discovery.It shows more and more practical applications,especially on the high density read head,magnetic sensor and the random access memory.Therefore,it not only has the scientific significance,but also has various application values for reaching GMR effect,which have been attracting people more and more attention in both the experimental and theoretical aspects.In this paper,we study the GMR effect of ferromagnetic in different magnetization directions or the GMR effect of ferromagnet ic combined with Schottky metal in2 DEG systems.The thesis consists of five chapters.In the first chapter,we briefly introduce two dimensional electron gas(2DEG),the research status and application of GMR effect and research background and significance of this paper.In the second chapter,the basic principle of transfer matrix is introduced in detail.After that the process of calculation is derived in detail.And then we simply introduced the calculation method of the non-uniform magnetic field.The third chapter mainly includes four aspects.First ly,the GMR effect of the system and the effect of different magnetization directions on the GMR effect are studied.The results show that the magnetic resistance ratio(MRR)strongly depends on the magnetization direction,especially when the magnetization direction is 180°.Secondly,we studied the influence of the size of the magnetic field on the GMR effect in detail and found that the MRR became large and the peak became broaden with the increase of magnetic field.The third part describes the relationship of the maximum MRR value and magnetic field intensity under different magnetic field intensity and the influence of different parameters on the MRR.It can be fou nd that the maximum MRR is closely related to the size of system parameters.Moreover,it increase s with the increase of magnetic field accords which is in accordance with the exponential growth law.The fourth part studies the MRR when the two magnetic strip s ha ve the same direction of magnetization,showing that the MRR value is minimum when the magnetization direction is 90 °.So a tunable GMR device can be designed by adjust ing magnetizing angle.In the fourth chapter,on basis of the previous research,we propose a GMR device by depositing two nanosized ferromagnetic(FM)and Schottky metal(SM)stripes on the top of the Ga As heterostructure.It can be theoretically studied the GMR effect of this hybrid nanostructure which consist s of size,width,and position of the voltage.The results show that the GMR effect of the device is quite significant.The peak of MRR became wider in the low energy region with increases of voltage.However,the peak decreased in the high energy area.It making the MRR moved towards the high energy region and gradually become smaller when the voltage becomes wider.In addition,we also found that when the SM moves between the two magnetic stripes,the GMR device has a very significant modulation effect.When the distance is the same,the MRR is symmetrical about the center,and the magnitude of the potential barrier does not change the symmetry of the MRR with respect to the center.But it will produce a large modulation effect on the MRR.Therefore,a tunable GMR device can be obtained by adjusting voltage.