33 research outputs found
Vibron-assisted spin excitation in a magnetically anisotropic nickelocene complex
The ability to electrically-drive spin excitations in molecules with magnetic anisotropy is key for high-density storage and quantum-information technology. Electrons, however, also tunnel via the vibrational excitations unique to a molecule. The interplay of spin and vibrational excitations offers novel routes to study and, ultimately, electrically manipulate molecular magnetism. Here we use a scanning tunneling microscope to electrically induce spin and vibrational excitations in a single molecule consisting of a nickelocene magnetically coupled to a Ni atom. We evidence a vibron-assisted spin excitation at an energy one order of magnitude higher compared to the usual spin excitations of nickelocene and explain it using first-principles calculations that include electron correlations. Furthermore, we observe that spin excitations can be quenched by modifying the Ni-nickelocene coupling. Our study suggests that nickelocene-based complexes constitute a model playground for exploring the interaction of spin and vibrations in the electron transport through single magnetic molecules
Vibron-assisted spin excitation in a magnetically anisotropic molecule
The electrical control and readout of molecular spin states are key for high-density storage. Expectations are that electrically-driven spin and vibrational excitations in a molecule should give rise to new conductance features in the presence of magnetic anisotropy, offering alternative routes to study and, ultimately, manipulate molecular magnetism. Here, we use inelastic electron tunneling spectroscopy to promote and detect the excited spin states of a prototypical molecule with magnetic anisotropy. We demonstrate the existence of a vibron-assisted spin excitation that can exceed in energy and in amplitude a simple excitation among spin states. This excitation, which can be quenched by structural changes in the magnetic molecule, is explained using first-principles calculations that include dynamical electroniccorrelations.We thank M. Ternes for providing his fitting program. This work was supported by the Agence Nationale de la Recherche (grants No. ANR-13-BS10-0016, ANR-11-LABX-0058 NIE and ANR-10-LABX-0026 CSC) and by the Agencia Española de Investigación (grants Nos. MAT2016-78293-C6-1-R and MDM-2016-0618). D.-J.C. and N.L. thank the MICINN (project RTI2018-097895-B-C44). M.-L.B. thanks the national computational center CINES and TGCC (GENCI project: A0030807364)
FeCoCp3 Molecular Magnets as Spin Filters
Metallorganic molecules have been proposed as excellent spin filters in
molecular spintronics because of the large spin-polarization of their
electronic structure. However, most of the studies involving spin transport,
have disregarded fundamental aspects such as the magnetic anisotropy of the
molecule and the excitation of spin-flip processes during electron transport.
Here, we study a molecule containing a Co and an Fe atoms stacked between three
cyclopentadienyl rings that presents a large magnetic anisotropy and a S=1.
These figures are superior to other molecules with the same transition metal,
and improves the spin-filtering capacities of the molecule. Non-equilibrium
Green's functions calculations based on density functional theory predict
excellent spin-filtering properties both in tunnel and contact transport
regimes. However, exciting the first magnetic state drastically reduces the
current's spin polarization. Furthermore, a difference of temperature between
electrodes leads to strong thermoelectric effects that also suppress spin
polarization. Our study shows that in-principle good molecular candidates for
spintronics need to be confronted with inelastic and thermoelectric effects
FeCoCp<sub>3</sub> Molecular Magnets as Spin Filters
Metallorganic molecules have been
proposed as excellent spin filters
in molecular spintronics because of the large spin polarization of
their electronic structure. However, most of the studies involving
spin transport have disregarded fundamental aspects such as the magnetic
anisotropy of the molecule and the excitation of spin-flip processes
during electron transport. Here, we study a molecule containing a
Co and an Fe atom stacked between three cyclopentadienyl rings, which
presents a large magnetic anisotropy and a <i>S </i>= 1. These figures are superior to other
molecules with the same transition metal and improves the spin-filtering
capacities of the molecule. Nonequilibrium Green’s functions
calculations based on density functional theory predict excellent
spin-filtering properties both in tunnel and contact transport regimes.
However, exciting the first magnetic state drastically reduces the
current’s spin polarization. Furthermore, a difference of temperature
between electrodes leads to strong thermoelectric effects that also
suppress spin polarization. Our study shows that in principle good
molecular candidates for spintronics need to be confronted with inelastic
and thermoelectric effects
Controlled spin switching in a metallocene molecular junction
Manipulating spin states of molecules in a controllable manner is essential to develop the molecule-based spintronics technologies. Here, Ormaza et al. show how to use the interaction between a single metallocene molecule and a metallic surface to reversibly switch spin from 1 to ½ in a junction
Atomic-scale spin sensing with a single molecule at the apex of a scanning tunneling microscope
Recent advances in scanning probe techniques rely on the chemical functionalization of the probe-tip termination by a single molecule. The success of this approach opens the prospect of introducing spin sensitivity through functionalization by a magnetic molecule. We used a nickelocene-terminated tip (Nc-tip), which offered the possibility of producing spin excitations on the tip apex of a scanning tunneling microscope (STM). When the Nc-tip was 100 picometers away from point contact with a surface-supported object, magnetic effects could be probed through changes in the spin excitation spectrum of nickelocene. We used this detection scheme to simultaneously determine the exchange field and the spin polarization of iron atoms and cobalt films on a copper surface with atomic-scale resolution