Upcoming Talks and Events:
Due to COVID-19 we've postponed all events in our Center. Updates to come!
april 2020
Event Details
Tobias Bilgeri 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
Event Details
Tobias Bilgeri
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.
Time
(Thursday) 4:00 pm - 5:00 pm KST
20aprallday23Event CancelledESR-STM WorkshopINL, Portugal(All Day)
Event Details
ESR-STM Workshop Due to COVID-19 the organizers have postponed the workshop. Updates to come! Visit Dates: April 20-23, 2020 Location: International Iberian Nanotechnology Laboratory, Portugal The discovery of Scanning Tunneling Microscope
Event Details
ESR-STM Workshop
Due to COVID-19 the organizers have postponed the workshop. Updates to come!
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
Time
april 20 (Monday) - 23 (Thursday)
Past Talks and Events:
march 2020
No Events
february 2020
11feb4:00 pm5:00 pmMarkus TernesResearch Center Jülich, Germany4:00 pm - 5:00 pm Saturn Seminar Room
Event Details
Markus Ternes Academic Affiliation: Research Center Jülich, Germany Research Area: Understing fundamental properties on the nanoscale with the focus on magnetic excitations and correlated systems. Research stay period: February 09 - 22,
Event Details
Markus Ternes
Academic Affiliation: Research Center Jülich, Germany
Research Area: Understing fundamental properties on the nanoscale with the focus on magnetic excitations and correlated systems.
Research stay period: February 09 – 22, 2020
Talk: February 11, 16:00 – 17:00
Sensing dark spins with a scanning tunneling microscope
Probing the spin of individual atoms and molecules on surfaces by means of inelastic electron tunneling spectroscopy (IETS) has since its introduction [1] developed to a very successful and widely used method in scanning tunneling microscopy [2]. Recently, IETS measurements have been also taken simultaneously on two magnetic impurities, one attached to the apex at the tip, the other one on the sample surface, revealing correlation-driven transport asymmetries, reminiscent of spinpolarized transport in a magnetic field [3]. In this experiment only the spin on the surface was spectroscopically active while the one on the tip was spectroscopically dark.
Here now I will show how the transport is significantly altered when the tunneling electron is interacting with both spins simultaneously; the one on sample and the one on the tip apex. Different to measurements on two S = 1spins which only showed the expected steps in the differential conductance at each individual excitation and the sum of both excitations [4] we observe complex IETS data when we use a functionalized tip apex with a high S = 3/2 Kondo system to probe a S = 2 Fe adatom on the CuN surface. To successfully simulate such spectrum, Kondo as well as potential scattering processes have to be taken into account whereby strong interference effects due to the fermionic nature of the tunneling electrons lead to novel selection rules [5].
The understanding of the transport rules is important because it enables one to use well understood surface supported spins to calibrate the spin at the ill defined tip apex. Successively, such spin can then be used as a well characterized mobile sensor with unprecedented spacial resolution [6].
References:
[1] A.J. Heinrich, J.A. Gupta, C.P. Lutz, and D.M. Eigler, Science 306, 466 (2004).
[2] M. Ternes, New J. Phys. 17, 063016 (2015).
[3] M. Muenks, P. Jacobson, M. Ternes, and K. Kern, Nature Comm. 8, 14119 (2017).
[4] M. Ormaza, et al., Nano Lett. 17, 1877 (2017).
[5] M. Ternes, C.P. Lutz, A.J. Heinrich, and W.-D. Schneider, arXiv:1908.08267 [cond-mat.meshall].
[6] B. Verlhac, et al., Science 366, 623 (2019).
Time
(Tuesday) 4:00 pm - 5:00 pm
13feb4:00 pm5:00 pmAli YazdaniPrinceton University, USA4:00 pm - 5:00 pm Saturn Seminar Room
Event Details
Ali Yazdani Academic Affiliation: Princeton University, USA Research Area: At the forefront of quantum materials research is the goal to understand how new quantum phenomena can emerge from the topology of
Event Details
Ali Yazdani
Academic Affiliation: Princeton University, USA
Research Area: At the forefront of quantum materials research is the goal to understand how new quantum phenomena can emerge from the topology of electronic wavefunctions or correlations arising from electron-electron interactions. The Yazdani Lab has contributed significantly to this research paradigm by harnessing the power of high-resolution scanning tunneling microscopy (STM) techniques to directly visualize electronic wavefunctions in topological and correlated quantum materials.
Talk: February 13, 2020, 16:00-17:00
Majorana in Chains and Hinges
In recent years, following pioneeringtheoretical work of Kitaev and others, we have learned how to engineermaterials that harbor quasiparticles that behave similar to fermions thatMajorana had first envisioned. In particular, there has been a focus onone-dimensional topological superconductor that harbor Majorana zero modes(MZM) that can potentially be used to make fault-tolerant topological quantumcomputation possible. We have proposed and implemented a platform forrealization of topological superconductivity and MZM in chains of magneticatoms on the surface of a superconductor. In this talk, I will review theseries of experiments on this platform that we have performed to establish thepresence of these exotic quasi-particle using spectroscopic mapping with thescanning tunneling microscope (STM). These include the most recent study of theunique spin signature of MZM. I focus most of the talk on a new platform wherewe use the one-dimensional helical hinge states of a higher order topologicalinsulators. In particular, I will show experiment demonstrating how combinationof magnetism and superconductivity on such one-dimensional states can also giverise to MZM that can be detected with an STM. Overall these experiments,illustrate how the power of spectroscopic imaging with the STM can be used tocharacterize novel quantum states of matter and visualize their exotic quasi-particles.
Time
(Thursday) 4:00 pm - 5:00 pm
Event Details
Markus Ternes Academic Affiliation: Quantum Nanoscience Division, Peter Grünberg Institut, Forschungszentrum Jülich Research Area: Understing fundamental properties on the nanoscale with the focus on magnetic excitations and correlated systems. Talk: February 21,
Event Details
Markus Ternes
Academic Affiliation: Quantum Nanoscience Division, Peter Grünberg Institut, Forschungszentrum Jülich
Research Area: Understing fundamental properties on the nanoscale with the focus on magnetic excitations and correlated systems.
Talk: February 21, 2020
Fitting Model for Spin Excitation
In this introductory lecture Prof. Markus Ternes will outline the fundamental considerations necessary to calculate the current transport through magnetic structures in a scanning tunneling setup using well established perturbation models. He will discuss the influence of higher order scattering on the spectrum and the limitations of the perturbative approach in this respect. Using the below provided scripts Prof.Ternes will discuss how one can use the ‘Graphical User Interface’ to simulate and fit single and complex spin structures in the “zero-current” and dynamical limit.
Participants interested in this lecture should bring their own laptop with them to directly use the scripts. For this, please install beforehand Scilab_6.0.2 (available without charge for Windows, Mac, and Linux from https://www.scilab.org/).
Time
(Friday) 1:30 pm - 2:30 pm
Event Details
Delegation from Forschungszentrum Jülich Academic Affiliation: Quantum Nanoscience Division, Peter Grünberg Institut, Forschungszentrum Jülich Visit Dates: February 24-28, 2020
Event Details
Delegation from Forschungszentrum Jülich
Academic Affiliation: Quantum Nanoscience Division, Peter Grünberg Institut, Forschungszentrum Jülich
Visit Dates: February 24-28, 2020
Time
february 24 (Monday) - 28 (Friday)
Event Details
Hervé Aubin Academic Affiliation: C2N, Department of Nanoelectronics, CNRS, France Research Area: STM spectroscopy, Superconductivity, Topological Insulators Research stay period: February 2020 - July 2020 Talk: February 25th, 16:00 – 17:00; Saturn Seminar
Event Details
Hervé Aubin
Academic Affiliation: C2N, Department of Nanoelectronics, CNRS, France
Research Area: STM spectroscopy, Superconductivity, Topological Insulators
Research stay period: February 2020 – July 2020
Talk: February 25th, 16:00 – 17:00; Saturn Seminar room (3F-367)
Anomalous Phase Shift and Spectral Signature of Equal Spin Triplet
A description of the talk will be updated soon!
Time
(Tuesday) 4:00 pm - 5:00 pm
