Spin Resolved Electronic Structures of Half-Metallic Ferromagnetic Single Crystalline Thin Films

利用自旋分辨光电子能谱研究了分子束外延(MBE)法生长的全Heusler铁磁合金晶体薄膜的自旋极化能带结构，并成功地获得了其自旋相关的电子结构。特别是首次观察到了负自旋极化表面态。这一发现将对理解隧道磁阻器件中磁输运现象的起源起到重要作用。我们也对面心立方铁超薄膜进行了类似的测量。观测到的自旋极化光电子能谱使我们能够估计Fe3D态的交换分裂的正确值。Heuler型铁磁合金NiMnSb，Ru_&lt；2-x&Gt；Fe_xCrZ(Z=Si，Ge)和Co_2MnX(X=Si，Ga，Ge)的块体电子结构已被软、硬X射线光电子能谱阐明。上述活动已在几次国际和国内会议上发表。

The aim of this work is to clarify the spin polarized band structures of crystalline thin films of the full Heusler-type ferromagnetic alloys grown by molecular beam epitaxy (MBE) method, which are expected to show completely spin-polarized (half-metallic) electronic states, utilizing spin-resolved photoelectron spectroscopy.The ultra-thin magnetic film of fcc Co/Cu(001) has been fabricated and its spin dependent electronic structures have been successfully obtained. Especially, the negatively spin-polarized surface state has been firstly observed. This finding would play an important role to understand the origin of the magnetic transport phenomena in the tunneling magneto-resistance devices.We have done the similar measurement also for fcc Fe ultra-thin films. The observed spin-polarized photoelectron spectra have enabled us to estimate a correct value of the exchange splitting of Fe 3d states.The electronic structures in the bulk of the Heuler-type ferromagnetic alloys, NiMnSb, Ru_<2-x>Fe_xCrZ (Z=Si, Ge) and Co_2MnX (X=Si, Ga, Ge), which are predicted to show "half-metallic" electronic structures, have been clarified by the soft and hard X-ray photoelectron spectroscopies.The above-mentioned activities have been presented at several international and domestic conferences.