...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Physical review >Origin of the spin polarization of magnetic scanning tunneling microscopy tips
【24h】

Origin of the spin polarization of magnetic scanning tunneling microscopy tips

机译：磁扫描隧道显微镜尖端的自旋极化的起源

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Using first-principles calculations, we demonstrate that the vacuum spin polarization of commonly used Fe-coated scanning tunneling microscopy (STM) tips is positive at the Fermi energy-opposite to that of Fe surfaces-and is often lower than expected from magnetic thin films. We consider single Fe atoms and pyramids of five Fe atoms on Fe (001) and (110) surfaces as models of STM tips. While the spin polarization of the local density of states (LDOS) at the apex atom of all considered lips is negative close lo the Fermi energy and dominated by minority d electrons, the spin polarization of the vacuum LDOS. crucial for the tunneling current, is positive and controlled by majority states of sp character. These states derive from the atomic 4$ and Ap orbitals and provide a large spillout of charge density into the vacuum. If we replace the Fe apex atom by a Cr, Mn, or Co atom, the vacuum spin polarization remains positive at the Fermi energy, and it is much enhanced for Cr or Mn in the favorable antiferromagnetic spin alignment with respect to the Fe tip body. At energies above the Fermi level, the spin polarization can change sign due to the contribution from antibonding minority d states. Single Mn and Fe atoms on a nonmagnetic tip provided, for example, by a Cu(001) surface display a similar vacuum LDOS with a small positive spin polarization in good agreement with recent experimental findings. For Cr-coated tips, we observe that the spin polarization can display a change in sign very close to the Fermi energy which can complicate the interpretation of the measured asymmetry in spin-polarized tunneling spectroscopy.
机译：使用第一性原理计算，我们证明了常用的铁涂层扫描隧道显微镜（STM）吸头的真空自旋极化在费米能上与铁表面相反，在费米能上为正，并且通常低于磁性薄膜的预期。 。我们将单个Fe原子和在Fe（001）和（110）表面上的五个Fe原子的金字塔视为STM尖端的模型。尽管在所有被考虑的嘴唇的顶点原子处的局部态密度（LDOS）的自旋极化在费米能量附近是负的，并由少数d电子支配，但真空LDOS的自旋极化。对于隧穿电流至关重要，它是正的，并且受sp特性的大多数状态控制。这些状态源自原子的4 $和Ap轨道，并向真空中大量散布电荷密度。如果我们用Cr，Mn或Co原子代替Fe顶点原子，则真空自旋极化在费米能量处保持为正，并且相对于Fe尖端体，Cr或Mn在反铁磁自旋取向良好的情况下大大增强了。 。在费米能级以上的能量下，由于反键少数d态的贡献，自旋极化会改变符号。例如，由Cu（001）表面提供的非磁性尖端上的单个Mn和Fe原子显示出类似的真空LDOS，具有小的正自旋极化，这与最近的实验发现非常吻合。对于镀铬电极头，我们观察到自旋极化可以显示出非常接近费米能量的符号变化，这会使自旋极化隧穿光谱法中测量的不对称性的解释复杂化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号