Single-molecule enhanced spin-flip detection (original) (raw)
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N ov 2 01 6 Single-molecule enhanced spin-flip detection
2016
We studied the spin-flip excitations of a double-decker nickelocene molecule (Nc) adsorbed on Cu(100) by means of inelastic tunneling spectroscopy (IETS), X-ray magnetic circular dichroism (XMCD) and density functional theory calculations (DFT). The results show that the molecule preserves its magnetic moment and magnetic anisotropy not only on Cu(100), but also in different metallic environments including the tip apex. Taking advantage of the efficient spin-flip excitation of this molecule, we show how such a molecular functionalized tip boosts the inelastic signal of a surface supported Nc by almost one order of magnitude thanks to a double spin-excitation process.
Atomic-scale spin sensing with a single molecule at the apex of a scanning tunneling microscope
Science, 2019
Single molecules sense spin Imaging surface magnetism, and, in particular, spin excitations of adsorbed molecules or films, is challenging. Verlhac et al. demonstrate spin-sensing capability by using the magnetic exchange interaction between a surface sample and the spin-excited states of a nickelocene molecule attached to a scanning tunneling microscope tip. The spatial dependence of the exchange field at the atomic scale enabled imaging of magnetic corrugation with atomic-scale lateral resolution for iron atoms and small islands of cobalt atoms absorbed on nonmagnetic copper surfaces. Science , this issue p. 623
Strategy for detection of electrostatic spin-crossover effect in magnetic molecules
Physical Review B, 2013
Scanning tunneling microscopy (STM) can be used to detect inelastic spin transitions in magnetic nanostructures comprising only a handful of atoms. Here we demonstrate theoretically that STM can uniquely identify the electrostatic spin-crossover effect, whereby the exchange interaction between two magnetic centers in a magnetic molecule changes sign as a function of an external electric field. The fingerprint of such effect is a large drop in the differential conductance as the bias increases. Crucially in the case of a magnetic dimer the spin-crossover transition inverts the order between the ground state and the first excited state, but does not change their symmetry. This means that at both sides of the conductance drop associated to the spin-crossover transition there are two inelastic transitions between the same states. The corresponding conductance steps split identically in a magnetic field and provide a unique way to identify the electrostatic spin crossover.
Controlled spin switching in a metallocene molecular junction
Nature Communications, 2017
The active control of a molecular spin represents one of the main challenges in molecular spintronics. Up to now spin manipulation has been achieved through the modification of the molecular structure either by chemical doping or by external stimuli. However, the spin of a molecule adsorbed on a surface depends primarily on the interaction between its localized orbitals and the electronic states of the substrate. Here we change the effective spin of a single molecule by modifying the molecule/metal interface in a controlled way using a low-temperature scanning tunneling microscope. A nickelocene molecule reversibly switches from a spin 1 to 1/2 when varying the electrode–electrode distance from tunnel to contact regime. This switching is experimentally evidenced by inelastic and elastic spin-flip mechanisms observed in reproducible conductance measurements and understood using first principle calculations. Our work demonstrates the active control over the spin state of single molecu...
Unveiling nickelocene bonding to a noble metal surface
Physical Review B, 2016
The manipulation of a molecular spin state in low-dimensional materials is central to molecular spintronics. The designs of hybrid devices incorporating magnetic metallocenes are very promising in this regard, but are hampered by the lack of data regarding their interaction with a metal. Here, we combine low-temperature scanning tunneling microscopy and density functional theory calculations to investigate a magnetic metallocene at the single-molecule level-nickelocene. We demonstrate that the chemical and electronic structures of nickelocene are preserved upon adsorption on a copper surface. Several bonding configurations to the surface are identified, ranging from the isolated molecule to molecular layers governed by van der Waals interactions.
Physical Review Letters, 2010
We investigate the spin-and energy dependent tunneling through a single organic molecule (CoPc) adsorbed on a ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning tunneling microscopy. Interestingly, the metal ion as well as the organic ligand show a significant spin-dependence of tunneling current flow. State-of-the-art ab initio calculations including also van-der-Waals interactions reveal a strong hybridization of molecular orbitals and surface 3d states. The molecule is anionic due to a transfer of one electron, resulting in a non-magnetic (S= 0) state. Nevertheless, tunneling through the molecule exhibits a pronounced spin-dependence due to spin-split molecule-surface hybrid states.
Addressing a Single Molecular Spin with Graphene-Based Nanoarchitectures
Molecular Architectonics, 2017
Finding reliable methods to exploit molecular degrees of freedom represents an intriguing problem involving the control of new mechanisms at the nanoscale and several technological challenges. Here, we report a novel approach to address a single molecular spin embedded in an electronic circuit. Our devices make use of molecules with well-defined magnetic anisotropy (TbPc 2) embedded in nanogapped electrodes obtained by electroburning graphene layers. Such devices work as molecular spin transistors allowing the detection of the Tb spin flip during the sweep of an external magnetic field. The spin readout is made by the molecular quantum dot that, in turns, is driven by an auxiliary gate voltage. In the general context of (spin-)electronics, these results demonstrate that: (1) molecular quantum dots can be used as ultra-sensitive detectors for spin flip detection and (2) the use of
Spin-flip scattering selection in a controlled molecular junction
arXiv: Strongly Correlated Electrons, 2017
A simple double-decker molecule with magnetic anisotropy, nickelocene, is attached to the metallic tip of a low-temperature scanning tunneling microscope. In the presence of a Cu(100) surface, the conductance around the Fermi energy is governed by spin-flip scattering, the nature of which is determined by the tunneling barrier thickness. The molecular tip exhibits inelastic spin-flip scattering in the tunneling regime, while in the contact regime a Kondo ground state is stabilized causing an order of magnitude change in the zero-bias conductance. First principle calculations show that nickelocene reversibly switches from a spin 1 to 1/2 between the two transport regimes.