The Study On Domain Wall Resistance Of Permalloy

The devices based on domain walls,because of its broad potential applications in the new generation of memories such as magnetic oscillator,magnetic logic devices,have attracted a great deal of attention nowadays.However,It is still very difficult to accurately locate the domain walls based on the motion of domain wall and the influence of the domain wall magnetoresistance on the magnetoresistance effect is not yet clear,which are very important for the design of the devices related to the domain wall.In this paper,we design a " Co/Py transverse coercivity heterostructure configuration"to detect the position of the domain wall and analyze the change of the magnetoresistance related to domain wall by doping different elements.The first chapter mainly introduces the new development of magnetic storage technology and the problems during this period of time,the overview and classification of magnetoresistive effect,the relates knowledge of domain and domain wall,and discussing the positioning problem of domain wall and the problem in which DWs either increase(positive DWR)or decrease(negative DWR)the resistance.The second chapter mainly introduces the preparation process and measurement methods of experimental sample.We mainly use the magnetron sputtering,mask technology,ion beam etching which belong to micro-processing technology.We introduced the working principle and workflow of the related equipment in detail,and summarized the precautions in it.In fact,we have made some improvements to the experimental process based on the micro-machining technology to make it more in line with the current experimental conditions.In sample test,the hysteresis loops and the magnetoresistance curve are measured by using a Vibrating Sample Magnetometer(VSM)and the MR option for VSM respectively,the domain images are achieved by Magneto-optical Kerr Microscope.The third chapter mainly introduces the analysis of the measurement data.We design a Co/Py magnetic transverse coercivity heterostructures sample and both M-M curve and MOKE microscopy images demonstrate the DWs exist inside Py layer at the border of the Co and Py,upon a external magnetic field alone the easy axis.We analyze the possible causes of the occurrence and put forward reasonable conjectures.A negative Py domain walls magnetoresistance was observed at room temperature by using a Co,Py'hard' and 'soft' magnetic transverse coercivity heterostructure thin film.More important,through doping the nonmagnetic 6.23%Cu and magnetic 5%Cr impurity inside the Py layer respectively,the sign of the domain wall resistance(DWR)transfer from negative to positive.In the fourth chapter,we summarize the design ideas and experimental results in this experiment and look forward to its possible future applications.In addition,we also conjecture on the conceptions of the future possible domain-wall storage devices.