Schneider Lucas, Beck Philip, Wiebe Jens, Wiesendanger Roland
Department of Physics, University of Hamburg, D-20355 Hamburg, Germany.
Sci Adv. 2021 Jan 20;7(4). doi: 10.1126/sciadv.abd7302. Print 2021 Jan.
A scanning tunneling microscope (STM) with a magnetic tip that has a sufficiently strong spin polarization can be used to map the sample's spin structure down to the atomic scale but usually lacks the possibility to absolutely determine the value of the sample's spin polarization. Magnetic impurities in superconducting materials give rise to pairs of perfectly, i.e., 100%, spin-polarized subgap resonances. In this work, we functionalize the apex of a superconducting Nb STM tip with such impurity states by attaching Fe atoms to probe the spin polarization of atom-manipulated Mn nanomagnets on a Nb(110) surface. By comparison with spin-polarized STM measurements of the same nanomagnets using Cr bulk tips, we demonstrate an extraordinary spin sensitivity and the possibility to measure the sample's spin-polarization values close to the Fermi level quantitatively with our new functionalized probes.
具有足够强自旋极化的磁性针尖扫描隧道显微镜（STM）可用于绘制原子尺度下样品的自旋结构，但通常无法绝对确定样品自旋极化的值。超导材料中的磁性杂质会产生一对完美的、即100%自旋极化的亚能隙共振。在这项工作中，我们通过附着铁原子，用这种杂质态对超导Nb STM针尖的顶端进行功能化，以探测Nb(110)表面上原子操纵的Mn纳米磁体的自旋极化。通过与使用Cr块状针尖对相同纳米磁体进行的自旋极化STM测量结果相比较，我们展示了非凡的自旋灵敏度，以及使用我们新的功能化探针定量测量接近费米能级的样品自旋极化值的可能性。
