Investigations of nano magnetic structures and surface electronic States by spin-polarized scanning tunneling spectroscopy

本项目的初步目标是：1)建立超高真空自旋极化扫描隧道光谱（SP-STS）； 2)利用SP-STS对Cr和Fe（001）薄膜进行磁成像。我们在第一年就完成了UHV-SP-STS实验装置的建立，并取得了一些科研成果。本项目3年的自旋极化扫描隧道光谱研究成果总结如下：1)超薄Cr（001）薄膜（<5nm）表面存在层状反铁磁有序的证据；2)台阶结构缺陷和螺旋位错对Cr（001）薄膜表面磁有序的影响；3)Cr（001）上超薄铁火石的生长和表面态。最重要的科学成就是“在厚度为9nm的Cr（001）薄膜上成功制备了高密度螺旋阶地及其磁成像”，观察到密集螺旋阶地导致的自旋受挫和不对称磁有序。连续微磁模拟证实了层状反铁磁有序的相当大的改变是由拓扑不对称引起的。该项目历时3年的科研成果已在《物理评论快报》、《物理评论B》、《应用物理杂志》等刊物上发表（共6篇），并在国际会议和国内会议上发表（共20篇），其中国际会议特邀演讲2次，国内会议特邀演讲6次。

The initial targets of this projects are 1)establishment of ultrahigh vacuum spin-polarized scanning tunneling spectroscopy (SP-STS) and 2)magnetic imaging of Cr and Fe(001) films by SP-STS. We finished the establishment of our experimental apparatus of UHV-SP-STS within the first year and we could get several scientific achievements.The scientific achievements of this 3 years projects by spin-polarized scanning tunneling spectroscopy can be summarized as follows : 1)Evidence of a layered antiferromagnetic order on ultrathin Cr (001) films (<5nm) 2)Consequences of structural defects of steps and screw dislocations on magnetic ordering of the Cr (001) film surface 3)Growth and surface states of ultrathin Fe flints on Cr(001).The most important scientific achievement is "a successful fabrication of high-density spiral terraces on Cr (001) films (9nm in thickness) and their magnetic imaging" Spin frustration and asymmetric magnetic ordering due to dense spiral terraces are observed. Sizable modification of the layered antiferromagnetic order is found to be originating from the topological asymmetry as confirmed by the continuum micromagnetic simulation.The scientific achievements of this 3 years projects were already published on Physical Review Letters, Physical Review B, and Journal of Applied Physics et al. (total 6 papers) and presented the international conferences and domestic meetings (total 20 presentations), including 2 invited talks on the international conferences and 6 invited talks on domestic meetings.