导　　师： 都有为;严密

学科专业： 080501

授予学位： 硕士

作　　者： ;

机构地区： 浙江大学

摘　　要： 铁氮化合物是一种重要的铁基合金,具有优异的耐腐蚀性,机械硬度和磁学性质,这使得其在钢材的保护层、催化媒介、磁性液体、磁记录介质和磁性薄膜器件等领域都有广泛的应用。其中α'-Fe16N2和yγ'-Fe4N相,由于具有特殊的磁性能,得到了广泛的研究。文献报道在Fe-N薄膜和α'-Fe16N2相中发现庞饱和磁化强度,该值比目前所有已应用的软磁材料的饱和磁化强度都高。另外,在Fe-N相中,γ'-Fe4N相结构简单,理论和实验上均发现γ'-Fe4N相有非常高的电子自旋极化率,可用于磁性薄膜器件,如磁隧道结等。 到目前为止,反应溅射、离子束沉积、分子束外延、化学气相沉积和离子注入等多种薄膜沉积方法用来制备特定结构的Fe-N薄膜,但只有极少数的课题组报道用PLD方法来制备Fe-N薄膜。PLD可以方便的实现在非平衡条件下制备特殊结构和性能的金属合金薄膜。在本文中,用PLD方法,在不同氮气气氛压力下沉积Fe-N薄膜。 在不同实验流程制备的Fe-N薄膜中,在8 mTorr氮气气氛压力下均发现薄膜饱和磁化强度异常升高的现象。而且XRD晶格常数计算发现不同实验流程,8mTorr氮气气氛压力下制备的Fe-N薄膜的中主相α-Fe相具有相同的晶格常数2.8705 A。根据XRD和CEMS分析判定,该饱和磁化强度异常升高是由于γ'-Fe4N和Fe两相混合的异质结构导致。8 mTorr氮气气压下制备的Fe-N薄膜的氮含量为9.1/%,接近a'-Fe16N2相的11.1/%。综合考虑薄膜磁性能和氮含量,可以确定PLD制备超高饱和磁化强度Fe-N薄膜的最佳氮气气氛压力在8 mTorr附近。 XRD相分析证明10 mTorr氮气气氛压力为制备单相γ'-Fe4N薄膜的最佳气氛压力条件。本论文中也首次在150℃相对低生长温条件下在Si/(100/)基片上成功制备/(001/)取向单相γ'-Fe4N薄膜,低温制备/(001/)取向单相γ'-Fe4N薄膜对磁性薄膜器件的集成应用有重大意义。/(001/)取向� Iron nitride is an important iron alloy with superior corrosion resistance, mechanical hardness and magnetic properties, which makes it very attractive for a number of applications including protective coating of steels, magnetic fluids, magnetic recording and catalysis, etc. The nitrogen poor phasesα'-Fe16N2 andγ'-Fe4N have stimulated the most intense research interest because of their excellent magnetic properties together with corrosion resistance. The giant saturation magnetization was observed in Fe-N films and a'-Fe16N2 phase, which is higher than any soft magnetic materials in existence. In terms ofy'-Fe4N, this is a simple structure Fe-N phase, and possessed some attractive magnetic properties, such as high spin-polarized transport, which makes it interesting to apply in magnetic thin film devices, e.g. magnetic tunnel junctions /(MTJs/). In order to fabricate special structure Fe-N films, various methods have been applied, e.g. reactive sputtering, ion beam assisted deposition, molecular-beam epitaxy, mechanical alloying, chemical vapor deposition and ion implantation, etc. However only few groups have previously reported results of Fe-N films deposited by the technology of reactive pulsed laser deposition /(PLD/). PLD is a facile method to grow special structure metallic films at nonequilibrium conditions. In the present work, Fe-N thin films have been deposited by reactive PLD at various nitrogen pressures. In series of Fe-N films, a anomalous Ms increase was observed for the films deposited at 8 mTorr nitrogen pressure. In addition, it was surprised to find that the a-Fe phase of Fe-N films deposited at 8 mTorr exhibited the same lattice constant of 2.8705A. According to the analysis of XRD and CEMS, this anomalous Ms increase in Fe-N films was speculated to due to a heterogeneous state ofγ'-Fe4N and Fe mixture. The calculated nitrogen concentration of the Fe-N film deposited at 8 mTorr is approximately 9.1/%, which is very close to the value of 11.1/% forα'-Fe16N2 phase. Considering the

关 键 词： 薄膜 脉冲激光沉积 织构 磁各向异性 穆斯堡尔谱 磁光克尔效应

领　　域： [理学] [理学]