Investigation Of Interfacial Structure In CoFe/TiZr Multilayers By Neutron Reflectometry

The interfacial structures of CoFe/TiZr alloy multilayers are investigated systemetically by neutron reflectometry, which alloys are the new developed and novel supermirror coatings for the international manufacturing polarizers and analysers. And besides, the analysis techniques of neutron reflection(NR) are studied too, such as the choice between algorithms of discretization and Nevot-Croce factor, which are two algorithms for calculating reflectivity to deal with the interfacial roughness in multilayers, resolution problems in design of reflectometor and data analysis, and programing the NR date analysis software NSC_NR.Algorithm of reflectivity plays an important role in drawing useful structural information from reflection data. It is necessary to choose a appropriate algorithm to calculate reflectivity in data analysis. The comparations between discretization and Nevot-Croce factor algorithm with different interfacial roughnesses show that Nevot-Croce factor can be use to calculate the reflectivity of not-very-rough multilayers (roughness is less than 1/3 layer thickness) at low Q range and save much time on fitting. If interfaces are very rough, such as serious diffusing, discretization algorithm is recommended. In practice,the choice of algorithm can be achieved according to the interfacial roughness and layer thickness. In discretization algorithm, the slope of the profile V(z) and the thickness of the multilayer should be employed to determine a reasonable F_step and z_step, in order to have the number of lames as small as possibel, generally, z_step obeys z_step～π/(10Q_max)Resolution is one of crucial parameters in design of reflectometor and data analysis. According to the definition of scattering vector resolution, two terms are involved, one is the beam collimation and the precision of measured angle, and another is the uncertainty of wavelength caused by the monochromator or velocity selector. Resolution as Q fuction is increased with Q for constant wavelength(CW) operation mode of reflectometers but decreased for time of flight(TOF) operation mode. Therefor, there is a equal-resolution point (Q_0c), TOF mode has an advantage in resolution at Q0c, contrarily, CW mode has an advantage at Q>Q_0c. As for the resolution in data analysis, dealing the uncertainty of wavelength and angle respectively is better than thinking both two as uncertainty of Q.Analysis of NR data to CoFe/TiZr alloy multilayers show: (a)At the point of supermirror transmission, not-equal-thickness bilayer( type B) is better than equal-thickness one(type A)...