Dresden 2014 – wissenschaftliches Programm
MA 20.2: Hauptvortrag
Dienstag, 1. April 2014, 15:30–16:00, BEY 118
Spin Interaction of Atoms studied with Ultrafast STM — •Sebastian Loth — Max Planck Institute for the Structure and Dynamics of Matter, Hamburg — Max Planck Institute for Solid State Research, Stuttgart
Spin-dependent interaction between magnetic atoms produces a variety of quantum phenomena ranging from superposition ground states and magnetic tunneling to quantum criticality. In this talk we will show that time-resolving scanning tunneling microscopy (STM) makes it possible to study these effects experimentally.
We engineer experimental representations of different Spin Hamiltonians by assembling transition metal atoms into arrays of different shape and elemental composition on the surface of a thin insulator/metal substrate. Inelastic electron tunneling and all-electronic pump-probe spectroscopy at GHz frequencies quantifies the energy level structure, energy loss mechanisms and spin lifetimes of the interacting spins [Science 329, 1628 (2010)]. Using this technique we identified a new approach to suppress magnetic tunneling in antiferromagnetic spin chains triggered by a phase transition from a singlet ground state to classical magnetic states [Science 335, 196 (2012)]. Magnetic tunneling can also be enhanced by combining atoms with different spin magnitude into chains that exhibit spin-correlated singlet ground states even at several nanometers length.
The time-domain information further enables non-local measurements of magnetic states shedding light onto possible pathways to controllably interact with atom-sized quantum spins.