Synthesis Of Two-dimensional Ferromagnetic Material And Research Of Spin Devices

Electronics has two intrinsic attributes:charge and spin degrees of freedom.The traditional electronic devices is controlled with the electronic charge of degrees of freedom.However,because of the existence of the quantum effect,the failure of"Moore's" lead the electronic devices based on electronic charge of degrees of freedom face the huge bottleneck in miniaturization and integration.As a result,people tried to use the spin degree of freedom to the preparation of new type of device.With the in-depth study of the spin degree of freedom,an emerging discipline "spintronics" was appeared.Spintronics research goal is electronic spin-polarized transport performance and development of devices based on the function spintronics.Compared to the traditional electronic devices,the devices based on spintronics have many advantages,including high speed,low power consumption,good stability,highly level of integration.In particular,carrier have the spin polarization characteristics in magnetic semiconductor materials.Thus the electronic two degrees of freedom can be used at the same time.It may develop the new functions of the microelectronic device.Then,changing the pattern of the modern information processing technology,which is operating the degrees of freedom of the electron charge and the electron spin in semiconductor at the same time for information transmission,processing and storage.On the other hand,since the graphene is confirmed as stable two-dimensional material,numerous two-dimensional materials show the unique properties in electrical,mechanical,optical and energy and so on,and are widely focused by researchers.The discoveries of intrinsic magnetic of two-dimensional materials lead to a new road for the development of two-dimensional materials.It is possible that the two-dimensional materials could be applied in spintronics devices.But,the mechanism of intrinsic magnetic of two-dimensional materials need to be researched,and the device design and preparation based on magnetic two-dimensional materials also need further exploration.This paper firstly report the synthesis of magnetic two-dimensional CrBr3,and confirme the existence of the intrinsic magnetic.Designing and developing the special device based on magnetic two-dimensional materials,and implements the controlable regulation of device performance.The specific content of this article summarized below:(1)The CrBr3 single crystal was synthesized successfully by the bulid-in tube furnace.A series of physical properties of single crystal CrBr3 was characterizated.The(00l)orientation and single crystal structure was confirmed by XRD.The single crystal structure and no-impurities was funther confirmed by XPS,TEM and Raman tests.The band gap of single crystal CrBr3 was demermined by the fluorescence spectrum,?1.34 eV.The ferromagnetic property of single crystal CrBr3 was determined by the magnetic testing,and the Curie temperature is 32 K,the coercive field is about 50 Oe,the saturation field is about 5000 Oe.The single crystal CrBr3 is verified magnetic anisotropy through the test of magnetic anisotropy,and the polarization axis is c axis.(2)The G/CrBr3 heterostructure device was successfully achieved using the mechanical stripping and heterojunction stack.The existence of magnetic proximity effect between graphene and CrBr3 was proved by testing the electrical transport properties of graphene.Appear of anomalous Hall component in graphene prove that the magnetic proximity effect introduce the ferromagnetism into graphene.With the increase of temperature,the magnetic proximity effect gradually weakened.But,the anomalous Hall components can also be observed when the temperature is higher than the Curie temperature of CrBr3,which is due to the pinning effect between graphene and CrBr3.The anomalous Hall components still can be observed when the direction of applied magnetic field parallel to the direction of current.And,there is an obvious negative magnetoresistance,which proved exist of spin polarized carier in graphene.In addition,the influence of two-carriers model is eliminated through the test of single graphene.Finally,the ferromagnetic graphene which induced by magnetic proximity effect can be identified.The establishment of this device leads a foundation for the future construction of spintronics device.(3)Tunneling junction based on CrBr3 was synthesized.The magnetic field dependence of tunneling junction was researched.The research found that there are platforms in the tunneling resistance with the change of magnetic field.These platform of resistance is because that applied magnetic field causes the electron spectrum to quantize into a series of Landau levels with nagnetic-assisted tunneling mechanism.The influence of tunneling mechanism on the tunneling proress has yet to be further researched.(4)A crossed structure of graphene devices was prepared.This device was fabricated through the heterojunction stack between two graphene with crossed angle.There exist two kinds of resistance because two paths in the precess of electric transport:internal resistance and tunneling resistance.There is competition relations between two kinds of resistance in the device.The ratio between two kinds of resistance can be quantitatively controlled by changing the test temperature of device.At high temperature,the internal resistance dominated,the change of resistance induced by the magnetic field will lead to the increase of overall resistance,which shows the positive magnetoresistance.At low temperature,tunneling resistance dominated,the change of the resistance induced by the magnetic field will lead to the decrease of the overall resistance,which shows the negative magnetoresistance.The magnetic logic inverter based on the crossed structure of graphene was fabricated,which can achieve controllable device performance.The establishement of inverter laid a foundation for the design of magnetic logic devices.