【作者】 石艳丽；

【导师】 刘祖黎；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2007， 硕士

【摘要】 继Fe/Cr多层膜巨磁电阻效应发现以后,巨磁电阻效应己成为国际研究的热点,人们发现过渡族铁磁金属或合金薄膜与非磁性金属构成多层膜后均可呈现巨磁电阻效应,其中以Co/Cu多层膜的GMR值最高,室温巨磁电阻效应可达65%。除多层膜外,在颗粒膜、隧道结,自旋阀中也发现了巨磁电阻效应。在巨磁电阻效应被发现后的第六年,IBM公司研制成巨磁电阻效应的读出磁头,将磁盘记录密度一下子提高了17倍,达5G b in2,而如今实验室的记录密度可达100G b in2,从而在与光盘的竞争中重新处于领先地位。由于巨磁电阻效应大,易使器件小型化、廉价化,除了读出磁头外同样可应用于测量位移、角度等传感器以及磁随机存储器中,具有巨大的应用前景,因而引起了广泛的关注。薄膜的生长结构对巨磁阻效应有着重要的影响,特别是膜与膜之间,膜与基底之间的粗糙度对巨磁阻效应有很大的影响,而薄膜的生长过程和生长机制在实验中是很难观测的,这就需要理论计算和模拟的帮助。在本文中,我们用一个基于动力学蒙特卡罗(kinetic Monte Carlo)方法的三维模型研究了Co薄膜在Cu(001)面的异质生长。我们模拟了在不同入射能量的情况下,外延沉积Co到Cu(001)基片上时,薄膜生长初期(沉积2500个粒子)和最终态(沉积20000个粒子)的形貌和表面粗糙度的情况,还对薄膜的生长方式做了一定的研究。研究结果表明,在膜厚小于两层时,薄膜的生长呈现岛状,膜厚大于两层时,薄膜以层状的方式生长。在薄膜的生长初期,存在一个能量转折点,在这个能量转折点,薄膜的表面粗糙度最小,而在最终态,薄膜的粗糙度随着入射能量的增加而减少,初态的生长方式对薄膜的最终态有一定的影响,在薄膜的内部仍有空位的存在。模拟的结果和实验基本吻合。更多还原

【Abstract】 The GMR effect has become an international researching hotspot after the discovery of GMR effect of Fe/Cr multilayers. People found that multilayers formed by ferromagnetic metal of transition family and nonmagnetic metal or by alloy film and nonmagnetic metal will take on GMR effect. The value of GMR of Co/Cu multilayers is the biggest which can reach 65% under room temperature,GMR effect is also discoveried in guanular film, tunneling junction resistance and spin valve. The magnetic head developed by IBM company with GMR effect increase the disk memory density 17 times which can reach 5G b in2 in the sixth year since GMR effect was discovered. The memorizing density in lab now can reach 100G b in2 which keep it ahead in the competition with CD. GMR effect also can be applied in sensor and MRAM, so it brings broad attention. Both theoretical and experimental studies have indicated that the GMR properties are sensitive to nanoscale structural features of the films and the intrinsic properties of the material. But the relationship between the GMR property and the structural properties, including the interfacial roughness between multilayer and the surface roughness of the substrate, has not yet been fully understood.In this paper, the Kinetic Monte Carlo simulations of the structure of ultrathin film of Co on Cu (001) are presented. The many-body, tight-binding potential model is used in the simulation to represent the interatomic potential. We simulate the film morphology and the surface roughness of heteroepitaxial Co film on Cu (001) substrate under the transient and final state conditions with various incident energies. The Co covered area and the thickness of the film growth of the first two layers are investigated. The simulation results show that the interfacial and surface roughness strongly depends on the incident energy. There exits a transition energy where the interfacial roughness is a minimum. The final film morphology is related to the early growth mode. In addition, there are deviations from ideal layer-by-layer growth at coverage from 0-2 monolayers (ML). The results are in agreement with experimental results.更多还原