Electron and Spin Correlations in Nano Carbon-Metal Hybrids

Nano-metals and magnetic materials have received considerable attention in recent years because of their importance in understanding fundamental physics in low dimensions as well as their high performance as electronic/spintronic components i.e. interconnects, high-density magnetic storage devices. This project aims at bulk scale control of low-dimensional electronic and magnetic functionalities via nanostructuring of metals inside carbon nanostructure templates. In the planned research we attempt to understand electron correlation, spin dynamics and their influence on the low dimensional ground state properties, such as the Tomonaga Luttinger liquid (TLL) in 1D metallic quantum-wires. We will use single-walled carbon nanotubes (SWCNT) and graphene layers as designer templates in which magnetic molecules and metals are incorporated and reacted in the confined space to transform into novel 1D quantum-wires and 2D quantum-networks. Recent developments on the synthesis of chirality selected or aligned SWCNT, graphene layers via chemical vapour deposition (CVD) methods as well as on the purification/separation techniques have made advanced carbon templates available on a bulk scale. This includes semiconducting, metallic or single-chirality SWCNT, aligned SWCNT and quasi-freestanding graphenes, which are used as templates. We will, e.g. study metal nanostructures encapsulated in various environments. This will allow us to analyse metal wires in semiconducting and metallic SWCNT in order to distinguish a purely 1D quantum-wire from a conductor of two coupled 1D quantum wires. These 1D metal hybrids with controlled environment will also allow us studying spectroscopically their correlated electronic and magnetic properties, such as the competition between the TLL and Peierls instability, as well as the magnet order and their impact on the correlated electronic ground state. These results will be compared to those from 2D graphene metal hybrid networks with selected metals. For this purpose we will use different spectroscopic techniques (Raman, optical, x-ray absorption, XMCD, photoemission, ESR and NMR) and SQUID. In addition, these nanocarbon-metal hybrids are packed in a van der Waals solid with interstitial spaces that can accommodate electron donors and acceptors. We will change the electronic and magnetic structures as function of intercalation doping by alkali metals and iron-trichloride and analyse the interplay between charge transfer, hybridization and chemical bonding in a controlled manner. This gives us a second handle to tailor the environment in-situ in UHV and allows for instance to directly monitor the transition from a 1D to a 3D ground state. In summary, this combined approach of a tailored synthesis of novel nanocarbon-metal hybrids and their spectroscopic analysis will give important insight into low dimensional spin and charge interactions. These results are the key for understanding how to tailor their properties for accessing the application potential in spintronics and high-density magnetic storage devices as final goal.

Nano-metals and magnetic materials have received considerable attention in recent years because of their importance in understanding fundamental physics in low dimensions as well as their high performance as electronic/spintronic components i.e. interconnects, high-density magnetic storage devices. This project "Electron and Spin correlations in nanocarbon-metal hybrids" aimed at bulk scale control of low-dimensional electronic and magnetic functionalities via nanostructuring of metals inside carbon nanostructure templates. We achieved a detailed basic understanding of electron correlation, spin dynamics and their influence on the low dimensional ground state properties in these tailored low dimensional hybrid systems of metals and low dimensional carbon allotropes. We used single-walled carbon nanotubes (SWCNT) and graphene layers as designer templates in which organic and magnetic molecules and metals are incorporated and reacted in the confined space to transform into novel 1D quantum-wires (carbyne as well as metals like Ni) and 2D quantum-networks (graphene ans well as transition metal di-chalcegonides (TMDC)). This research project has allowed via combined approach of a tailored synthesis of novel nanocarbon-metal hybrids and their spectroscopic analysis important insight into low dimensional spin and charge interactions. It was extremely successful and led to 32 peer reviewed publications including 16 highlights (3 AcsNano, 4 Nanoletters, 1 Physical Review Letters, 1 Angewandte Chemie, 4 Nanoscale, 1 Jornal of materials chemistry, 1 2D Materials and 1 Nature). These results are the key for understanding how to tailor their properties for accessing the application potential in spintronics and high-density magnetic storage devices as final goal. In addition, we observed during the project the need to perform further developments on techniques how to measure the electronic and vibrational excitation spectrum of individual metal-nanotube hybrids. This was achieved by intensifying a very successful collaboration with Prof. Kazu Suenaga's group regarding electron energy-loss spectroscopy inside an electron microscope using nanocarbons as probe which was in part supported by the project. This resulted in several highlights including a Nature paper unraveling the phonon dispersion of individual graphene layers. This publication is the key publication and scientific basis of a new just accepted ERC-Synergy project MORE-TEM, which will start in Mai 2021 and is led by the Prof. Thomas Pichler as principle investigator.