Local Investigation of Single Magnetic Molecules with Scanning Tunneling Microscopy


Book Description

We worked on different magnetic molecules containing 3d and 4f magnetic centers. Their growth on metallic surfaces, topographies, spin states, magnetic properties and electron transport were locally investigated by using scanning tunneling microscopy (STM) at temperatures down to 30mK. The main achievement of this dissertation reveals the abrupt switching of crystal fields during formation of molecular contacts.




Light Emission from Single Self-decoupled Molecules in a Scanning Tunnelling Microscope


Book Description

In this work, a clear pathway is presented to achieve well-defined electronically decoupled chromophores from metallic leads without requiring additional insulating layers. To study such self-decoupled molecules, STM equipped with an efficient light detection setup has been used. Results show that the chromophores mounted on tripodal molecular platforms adsorbed on a gold surface present well-defined and efficient electroluminescence down to the single-molecule level.




Local Probing of a Superconductor’s Quasiparticles and Bosonic Excitations with a Scanning Tunnelling Microscope


Book Description

Complementary to scattering techniques, scanning tunnelling microscopy provides atomic-scale real space information about a material's electronic state of matter. State-of-the-art designs of a scanning tunnelling microscope (STM) allow measurements at millikelvin temperatures with unprecedented energy resolution. Therefore, this instrument excels in probing the superconducting state at low temperatures and especially its local quasiparticle excitations as well as bosonic degrees of freedom.




Molecular Motor Based on Single Chiral Tripodal Molecules Studied with STM


Book Description

This work presents a single molecular motor driven by the current in an STM. Its chiral functional group is supposed to perform a rotation in a preferred direction, proven by Binomial tests to be statistically significant. The rotation is proposedly driven by the chiral-induced spin selectivity effect (CISS). However, the studies of the rotation on the dependence on the lateral tip position, voltage and current indicate that he CISS is unlikely to cause the preferred rotation direction.




Scanning Tunneling Spectroscopy of Magnetic Bulk Impurities


Book Description

Magnetic impurities in a non-magnetic host metal have been actively explored in condensed matter physics in recent last decades. From both fundamental and applied viewpoints these systems are very interesting because they can exhibit strong electronic correlations that give rise to various fascinating phenomena beyond the single particle picture. Up to now our understanding of the underlying processes remains limited due to difficulties involved in measuring these systems on a microscopic scale. With their unique control, scanning tunneling microscopy (STM) and spectroscopy (STS) allow for the first time investigations of phenomena occurring on very small length and energy scales. Here, single magnetic iron and cobalt atoms embedded beneath a metal surface are investigated using these techniques. In particular, the transition from single impurity Kondo physics to two interacting impurities is studied in real space. This thesis contains a comprehensive description of the STM /STS technique, sub-surface impurities, as well as single- and two-impurity Kondo physics - and as such offers a valuable introduction to newcomers to the field.




Quantum Sensing Experiments with Superconducting Qubits


Book Description

Quantum sensing is a vast and emerging field enabling in-situ studies of quantum systems and hence the development of quantum hybrid systems. This work creates the fundament of direct superconducting-magnetic hybrid systems by developing a local microwave sensing scheme and studying the influence of a static magnetic field on a superconducting qubit. Finally, a proof-of-principle hybrid system is demonstrated, which opens the path towards superconducting-magnetic quantum circuits.







Elastic and Inelastic Scanning Tunneling Spectroscopy on Iron-Based Superconductors


Book Description

Within this work, the pairing mechanism of conventional (Pb) and unconventional superconductors (SrFe2(As1-xPx )2 , FeSe, FeSe/STO) was investigated experimentally by means of elastic and inelastic tunneling spectroscopy at temperatures down to 30 mK. The distinction between elastic and inelastic contributions to tunneling data was elaborated. The results help to identify conventional (phonon-mediated) and unconventional (e.g. spin-?uctuation mediated) superconductivity.




Single-Molecule Magnets


Book Description

Concise overview of synthesis and characterization of single molecule magnets Molecular magnetism is explored as an alternative to conventional solid-state magnetism as the basis for ultrahigh-density memory materials with extremely fast processing speeds. In particular single-molecule magnets (SMM) are in the focus of current research, both because of their intrinsic magnetization properties, as well as because of their potential use in molecular spintronic devices. SMMs are fascinating objects on the example of which one can explain many concepts. Single-Molecule Magnets: Molecular Architectures and Building Blocks for Spintronics starts with a general introduction to single-molecule magnets (SMM), which helps readers to understand the evolution of the field and its future. The following chapters deal with the current synthetic methods leading to SMMs, their magnetic properties and their characterization by methods such as high-field electron paramagnetic resonance, paramagnetic nuclear magnetic resonance, and magnetic circular dichroism. The book closes with an overview of radical-bridged SMMs, which have shown application potential as building blocks for high-density memories. Covers a hot topic – single-molecule magnetism is one of the fastest growing research fields in inorganic chemistry and materials science Provides researchers and newcomers to the field with a solid foundation for their further work Single-Molecule Magnets: Molecular Architectures and Building Blocks for Spintronics will appeal to inorganic chemists, materials scientists, molecular physicists, and electronics engineers interested in the rapidly growing field of study.




Adding nonlinearity to an electromagnetic-magnonic quantum hybrid device


Book Description

In this book, hybrid systems based on yttrium-iron-garnet (YIG), three dimensional microwave cavity resonators, and superconducting transmon qubits, are investigated by continuous wave and pulsed microwave spectroscopy. Limitations to the magnetic linewidth in the quantum regime are identified and coherent exchange between a magnon and a superconducting qubit are demonstrated. Finally, a first step towards a strongly coupled hybrid system containing all three components is demonstrated.