Publications de Stefano Rusponi

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We determine the magnetic properties of individual Co atoms adsorbed on graphene (G) with x-ray absorption spectroscopy and magnetic circular dichroism. The magnetic ground state of Co adatoms strongly depends on the choice of the metal substrate on which graphene is grown. Cobalt atoms on G/Ru(0001) feature exceptionally large orbital and spin moments, as well as an out-of-plane easy axis with large magnetic anisotropy. Conversely, the magnetic moments are strongly reduced for Co/G/Ir(111), and the magneti

In sharp contrast to previous studies on FeRh bulk, thin films, and nanoparticles, we report the persistence of ferromagnetic order down to 3 K for size-selected 3.3 nm diameter nanocrystals embedded into an amorphous carbon matrix. The annealed nanopartic ...

We investigate the spin relaxation of Ho single atom magnets on MgO/Ag(100) as a function of temperature and magnetic field. We find that the spin relaxation is thermally activated at low field, while it remains larger than 1000 s up to 30 K and 8 T. This ...

We present a new method to engineer the charge carrier mobility and its directional asymmetry in epitaxial graphene by using metal cluster superlattices self-assembled onto the moiré pattern formed by graphene on Ir(111). Angle-resolved photoemission spectroscopy reveals threefold symmetry in the band structure associated with strong renormalization of the electron group velocity close to the Dirac point giving rise to highly anisotropic Dirac cones. We further find that the cluster superlattice also affect

We performed a combined theoretical and experimental investigation of the orbital magnetism and magnetocrystalline anisotropy of isolated Co and Fe adatoms on Pd(111) and Rh(111). Theoretical calculations of the spin and orbital moments are based on ab ini ...

The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum ( 111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic a

The magnetic properties of individual Fe and Co atoms as well as of small Fe clusters adsorbed on two atomic layers of Al2O3 grown on Ni3Al(111) have been investigated by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. We find ratios o ...

Scanning tunneling microscopy (STM) has been used to investigate the nucleation and stability of iron clusters on the Al2O3/Ni3Al (111) surface as a function of coverage and annealing temperature. We show that atomic beam deposition of iron leads to hexago ...

We have combined magneto-optical Kerr effect, scanning tunneling microscopy, and x-ray magnetic circular dichroism to study the magnetic properties and the morphology of Fe nanoparticles grown on 2 ML thick Al2O3/Ni3Al(111)-(root 67 x root 67)R12.2 degrees with and without Pd seeding. The Ni3Al(111) substrate is ferromagnetic and shows two transition temperatures. The first, T-C1 = 81 +/- 3 K, is attributed to a 20-30 nm thick slightly Ni enriched region; the second, T-C2 = 240 +/- 12 K, is attributed to a

We have used x-ray photoemission electron microscopy (XPEEM) and x-ray absorption spectroscopy (XAS) to characterize MnxGe1-x and CryMnxGe1-x-y films grown by molecular beam epitaxy. The surface layers of the as-grown films probed by XPEEM present segregat ...

We demonstrate that electrospray deposition enables the fabrication of highly periodic self-assembled arrays of Fe4H single molecule magnets on graphene/Ir(111). The energetic positions of molecular states are probed by means of scanning tunneling spectros ...

The magnetic propertiesof transition-metal ions aregenerallydescribed by the atomic spins of the ions and their exchange coupling.The orbital moment, usually largely quenched due the ligand field,is then seen as a perturbation. In such a scheme, S = 1/2 io ...

Single lanthanide atoms and molecules are promising candidates for atomic data storage and quantum logic due to the long lifetime of their magnetic quantum states. Accessing and controlling these states through electrical transport requires precise knowled ...

We describe a setup for the x-ray detection of ferromagnetic resonance in the longitudinal geometry using element-specific transmission measurements. Thin magnetic film samples are placed in a static magnetic field collinear with the propagation direction ...

We perform on-surface synthesis of single-ion molecular magnets on an Ag(111) surface and characterize their morphology, chemistry, and magnetism. The first molecule we synthesize is TbPc2 to enable comparison with chemically synthesized and subsequently s ...

We have studied the evolution of the magnetic properties of monolayer-high cobalt islands on a Pt(111) surface as function of their exposure to oxygen. We observe a sequential quenching of magnetic anisotropy and magnetic moment. For minute exposures to oxygen this leads to an enhancement of the maximum susceptibility of up to 66% for chi". We show that the reason for the reduction of the anisotropy before the one of the moment is due to preferential oxygen adsorption at the island edges, which are the main

Advances in growth technology of oxide materials allow single atomic layer control of heterostructures. In particular delta doping, a key materials' engineering tool in today's semiconductor technology, is now also available for oxides. Here we show that a ...

Clusters and islands of Fe atoms have been prepared by noble gas buffer layer assisted growth as well as by standard molecular beam epitaxy on Pt substrates. Xe buffer layers have been utilized to promote the formation of compact, relaxed Fe clusters with ...

We demonstrate that the giant spin contrast observed by scanning tunneling microscopy for double-layer Coislands on Pt(111) is caused by adsorbates at the apex of the Cr-coated W tip. The most likely candidate, in ab initio simulations, is hydrogen. Here, ...

Single atom magnets offer the possibility of magnetic information storage in the most fundamental unit of matter. Identifying the parameters that control the stability of their magnetic states is crucial to design novel quantum magnets with tailored proper ...

Stefano Rusponi

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Tailoring the Magnetism of Co Atoms on Graphene through Substrate Hybridization

Low Temperature Ferromagnetism in Chemically Ordered FeRh Nanocrystals

Unconventional Spin Relaxation Involving Localized Vibrational Modes in Ho Single-Atom Magnets

Highly Anisotropic Dirac Cones in Epitaxial Graphene Modulated by an Island Superlattice

Magnetocrystalline anisotropy energy of Co and Fe adatoms on the (111) surfaces of Pd and Rh

Giant magnetic anisotropy of single cobalt atoms and nanoparticles

Magnetic anisotropy of Fe and Co adatoms and Fe clusters magnetically decoupled from Ni_{3}Al(111) by an alumina bilayer

Nucleation of ordered Fe islands on Al2O3/Ni3Al(111)

Interlayer exchange coupling in ordered Fe nanocluster arrays grown on Al2O3/Ni3Al(111)

Surface characterization of MnxGe1-x and CryMnxGe1-x-y dilute magnetic semiconductors

Uniaxial 2D Superlattice of Fe-4 Molecular Magnets on Graphene

Large Orbital Moment of Two Coupled Spin-Half Co Ions in a Complex on Gold

Mapping Orbital-Resolved Magnetism in Single Lanthanide Atoms

Longitudinal detection of ferromagnetic resonance using x-ray transmission measurements

Magnetic properties of on-surface synthesized single-ion molecular magnets

Oxidation induced enhanced magnetic susceptibility of Co islands on Pt(111)

Tunable spin polarization and superconductivity in engineered oxide interfaces

Magnetism of Fe clusters and islands on Pt surfaces

Role of hydrogen in giant spin polarization observed on magnetic nanostructures

Correlation between Electronic Configuration and Magnetic Stability in Dysprosium Single Atom Magnets