Academic Affiliation: C2N, Department of Nanoelectronics, CNRS, France

Research Area: STM spectroscopy, Superconductivity, Topological Insulators

Research stay period: February 2020 – July 2020

Academic Affiliation: Center for Quantum Nanoscience

Date: April 9, 2020

Time: 16:00 – 17:00

Upgrade of a scanning tunneling microscope for spin resonance

The addition of electron spin resonance to the STM-toolbox greatly increased the physical phenomena accessible in STM experiments. For this reason we upgraded throughout 2017-2018 a homebuilt, low temperature, high magnetic field STM to become world’s second ESR-STM. I will give a general introduction into ESR-STM and describe in detail the technical steps needed for the upgrade.

Academic Affiliation: Center for Quantum Nanoscience

Date: April 16, 2020

Time: 16:00 – 17:00

ESR-STM studies of Dy and FePc on MgO

In 2016 it was discovered that individual Ho atoms on MgO can show magnetic bistability with record breaking temporal, thermal and magnetic field stability. During our first research project as part of my stay at QNS, we discovered that Dy atoms in many ways exceed the stability of Ho. We find anisotropy barriers roughly twice as large as in Ho, as well as superior robustness against low field demagnetization processes as inferred from a novel ESR-STM technique. We believe that this is a result of a similar physical environment as found for Ho but with additional symmetry protection due to a non-integer spin ground state in the 4f⁹ configuration of Dy. Furthermore we demonstrate facile atomic manipulation, which allows to engineer precise local magnetic fields with sub-nanometer precision.

During our second research project, we demonstrate for the first time electron spin resonance measurements of individually addressable molecular spins on a surface. Using the spin-1/2 system FePc, we carry out ESR measurements in a vector field and find an isotropic moment of 0.97muB. We coherently manipulate the spin and find coherence times of 42 ns in Rabi experiments. Using a Hahn echo scheme, we show that the intrinsic coherence time is 180 ns with tunneling electrons presenting the dominant source of decoherence. Finally we demonstrate that FePc molecules self-assemble in a commensurate lattice while at the same time retaining the spin properties of individual molecules. We spatially resolve the molecular interactions using local magnetic resonance imaging and demonstrate that the phase coherence time is fully preserved in molecules within a lattice.

Visit Dates: April 20-23, 2020

Location: International Iberian Nanotechnology Laboratory, Portugal

The discovery of Scanning Tunneling Microscope (STM) Electron Spin Resonance (ESR) is opening new venues in surface quantum nanoscience. This workshop will bring together experts in this emerging area to present latest developments and discuss future work.

Participation only by invitation