报告题目：A close-up look at magnetism

报 告 人：Dr. Sebastian Loth，Center for Free-Electron Laser Science, Hamburg，Max-Planck Institute for Solid State Research, Stuttgart, Germany

报告时间：9月5日下午4:00-5:00

报告地点：物理系三楼报告厅

报告摘要：The scanning tunneling microscope has changed our view of the nanoworld. Atoms are no longer intangible objects. They can be imaged individually and even manipulated into structures that do not exist naturally. We use this capability to test how classical concepts of magnetism emerge from the quantum mechanical behavior of individual atoms. We use a low-temperature scanning tunneling microscope (STM) and assemble the nanostructures from different transition metal elements. Inelastic tunneling spectroscopy serves as a highly sensitive tool to achieve chemical identification of the atoms and to resolve their magnetic properties.

The time-dependent evolution of a spin holds the key to understanding its stability and interaction mechanism with the environment. Therefore we combine inelastic tunneling spectroscopy with electronic pump probe methods to increase the STM’s time resolution into the nanosecond range. With this technique we can follow the evolution of magnetic states as we build a nanostructure one atom at a time. This makes it possible to optimize arrangements of atoms that either enhance or reduce magnetic stability. We identified a new route to create stable magnetic states using antiferromagnetic spin-spin interaction enabling a model demonstration of dense magnetic memory with only 12 atoms per bit (Science 335 196, 2012).

These experiments show a promising route towards rapid prototyping of quantum magnetic spin structures with control over static and dynamic properties by atom assembly in the STM.