Imaging and Manipulating Single and Interacting Spins on Surfaces: Towards Atomic-Scale Spin Devices

Spin-Polarized Scanning Tunneling Microscopy (SP-STM) provides new insight into spin structures at a length scale and a sensitivity level which are inaccessible by other magnetic-sensitive measurement techniques [1]. The combination of atomic resolution in direct space, single spin sensitivity, and high energy resolution nowadays offers unique possibilities for probing spin-dependent states and interactions in natural or artificially created nanostructures [2]. The ultimate goal has been the combination of spin-resolved imaging with atomic resolution and magnetometry at the single-atom level in order to probe spin states and magnetic interactions of individual adatoms and nanostructures at solid surfaces quantitatively and in a most direct way. This challenging goal has been achieved by operating a SP-STM system at temperatures below 1 Kelvin and in external magnetic fields up to several Tesla. The new method of single-atom magnetometry with an unprecedented degree of magnetization measurement sensitivity is applicable to metallic [3, 4] as well as to semiconducting [5] and molecular systems [6]. The combination of single-atom manipulation techniques and single-atom magnetometry has recently led to the first demonstration of atomic-scale spin logic devices based solely on spin- rather than charge-transport for realizing computation and information transmission at the atomic level. \\[4pt] [1] R. Wiesendanger, Rev. Mod. Phys. 81, 1495 (2009).\\[0pt] [2] D. Serrate, et al., Nature Nanotechnology 5, 350 (2010). \\[0pt] [3] F. Meier, et al., Science 320, 82 (2008). \\[0pt] [4] L. Zhou, et al., Nature Physics 6, 187 (2010). \\[0pt] [5] A. A. Khajetoorians, et al., Nature 467, 1084 (2010). \\[0pt] [6] J. Brede, et al., Phys. Rev. Lett. 105, 047204 (2010).