Publications (41)
Theory of single spin inelastic tunneling spectroscopy
J. Fernandez-Rossier
Recent work shows that inelastic electron scanning tunneling microscope (STM) probes the elementary spin excitations of a single and a few magnetic atoms in a thin insulating layer…
Exciton condensates in semiconductor quantum wells emit coherent light
J. Fernandez-Rossier, C. Tejedor, R. Merlin
We show that a quasi-two dimensional condensate of optically active excitons emits coherent light even in the absence of population inversion. This allows an unambiguous and clear…
Consequences of Kondo exchange on quantum spins
F. Delgado, C. F. Hirjibehedin, J. Fernandez-Rossier
When individual quantum spins are placed in close proximity to conducting substrates, the localized spin is coupled to the nearby itinerant conduction electrons via Kondo exchange.…
Performance limits of graphene-ribbon-based field effect transistors
F. Munoz-Rojas, J. Fernandez-Rossier, L. Brey +1
The performance of field effect transistors based on an single graphene ribbon with a constriction and a single back gate are studied with the help of atomistic models. It is shown…
Anisotropic magnetoresistance in nanocontacts
D. Jacob, J. Fernandez-Rossier, J. J. Palacios
We present ab initio calculations of the evolution of anisotropic magnetoresistance (AMR) in Ni nanocontacts from the ballistic to the tunnel regime. We find an extraordinary enhan…
Optical control of the spin state of two Mn atoms in a quantum dot
L. Besombes, C. L. Cao, S. Jamet +2
We report on the optical spectroscopy of the spin of two magnetic atoms (Mn) embedded in an individual quantum dot interacting with either a single electron, a single exciton and s…
Spin-transfer torque on a single magnetic adatom
F. Delgado, J. J. Palacios, J. Fernandez-Rossier
We theoretically show how the spin orientation of a single magnetic adatom can be controlled by spin polarized electrons in a scanning tunneling microscope configuration. The under…
A theory of ferromagnetism in planar heterostructures of (Mn,III)-V semiconductors
J. Fernandez-Rossier, L. J. Sham
A density functional theory of ferromagnetism in heterostructures of compound semiconductors doped with magnetic impurities is presented. The variable functions in the density func…
Fermi-edge singularities in linear and non-linear ultrafast spectroscopy
D. Porras, J. Fernandez-Rossier, C. Tejedor
We discuss Fermi-edge singularity effects on the linear and nonlinear transient response of an electron gas in a doped semiconductor. We use a bosonization scheme to describe the l…
Emergent quantum matter in graphene nanoribbons
J. L. Lado, R. Ortiz, J. Fernandez-Rossier
In this book chapter, we introduce different schemes to create quantum states of matter in engineered graphene nanoribbons. We will focus on the emergence of controllable magnetic…
Spin depolarization in the transport of holes across GaMnAs/GaAlAs/p-GaAs
L. Brey, J. Fernandez-Rossier, C. Tejedor
We study the spin polarization of tunneling holes injected from ferromagnetic GaMnAs into a p-doped semiconductor through a tunneling barrier. We obtain an upper limit to the spin…
Spin degree of freedom in two dimensional exciton condensates
J. Fernandez-Rossier, C. Tejedor
We present a theoretical analysis of a spin-dependent multicomponent condensate in two dimensions. The case of a condensate of resonantly photoexcited excitons having two different…
Giant magnetoresistance in ultra-small Graphene based devices
F. Muñoz-Rojas, J. Fernandez-Rossier, J. J. Palacios
By computing spin-polarized electronic transport across a finite zigzag graphene ribbon bridging two metallic graphene electrodes, we demonstrate, as a proof of principle, that dev…
Electronic Structure of gated graphene and graphene ribbons
J. Fernandez-Rossier, J. J. Palacios, L. Brey
We study the electronic structure of gated graphene sheets. We consider both infinite graphene and finite width ribbons. The effect of Coulomb interactions between the electrically…
Influence of a Uniform Current on Collective Magnetization Dynamics in a Ferromagnetic Metal
J. Fernandez-Rossier, M. Braun, A. S. Núñez +1
We discuss the influence of a uniform current, , on the magnetization dynamics of a ferromagnetic metal. We find that the magnon energy has a current-induce…
Exciton Beats in GaAs Quantum Wells: Bosonic Representation and Collective Effects
J. Fernandez-Rossier, C. Tejedor, R. Merlin
We discuss light-heavy hole beats observed in transient optical experiments in GaAs quantum wells in terms of a free-boson coherent state model. This approach is compared with desc…
The emergence of classical behavior in magnetic adatoms
F. Delgado, S. Loth, M. Zielinski +1
A wide class of nanomagnets shows striking quantum behavior, known as quantum spin tunneling (QST): instead of two degenerate ground states with opposite magnetizations, a bonding-…
Ultrafast Coherent Spectroscopy of the Fermi Edge Singularity
Diego Porras, J. Fernandez-Rossier, C. Tejedor
In this work we present a theoretical description of the transient response of the Fermi Edge Singularity (FES). We study the linear and the nonlinear response of an n-doped QW to…
Anisotropic magnetoresistance in single electron transport
J. Fernandez-Rossier, R. Aguado, L. Brey
We study the effect of magnetic anisotropy in a single electron transistor with ferromagnetic electrodes and a non-magnetic island. We identify the variation of the chemical…
Single Electron Transport in electrically tunable nanomagnets
J. Fernandez-Rossier, R. Aguado
We study a single electron transistor (SET) based upon a II-VI semiconductor quantum dot doped with a single Mn ion. We present evidence that this system behaves like a quantum nan…
Microscopic theory for quantum mirages in quantum corrals
D. Porras, J. Fernandez-Rossier, C. Tejedor
Scanning tunneling microscopy permits to image the Kondo resonance of a single magnetic atom adsorbed on a metallic surface. When the magnetic impurity is placed at the focus of an…
Exchange mechanism for electron paramagnetic resonance of individual adatoms
J. L. Lado, A. Ferron, J. Fernandez-Rossier
We propose a new universal mechanism that makes it possible to drive an individual atomic spin using a spin polarized scanning tunnel microscope (STM) with an oscillating electric…
Intrinsic spin noise in MgO magnetic tunnel junctions
F. Delgado, K. Lopez, R. Ferreira +1
We consider two intrinsic sources of noise in ultra-sensitive magnetic field sensors based on MgO magnetic tunnel junctions, coming both from Mg nuclear spins (, 10%…
Spin splitting in a polarized quasi-two-dimensional exciton gas
L. Vina, L. Munoz, E. Perez +3
We have observed a large spin splitting between "spin" and heavy-hole excitons, having unbalanced populations, in undoped GaAs/AlAs quantum wells in the absence of any ex…
Quantum spin Hall phase in multilayer graphene
N. A. Garcia-Martinez, J. L. Lado, J. Fernandez-Rossier
The so called quantum spin Hall phase is a topologically non trivial insulating phase that is predicted to appear in graphene and graphene-like systems. In this work we address the…
Mn-doped II-VI quantum dots: artificial molecular magnets
J. Fernandez-Rossier, Ramon Aguado
The notion of artifical atom relies on the capability to change the number of carriers one by one in semiconductor quantum dots, and the resulting changes in their electronic struc…
Quantum Anomalous Hall effect in graphene coupled to skyrmions
J. L. Lado, J. Fernandez-Rossier
Skyrmions are topologically protected spin textures, characterized by a topological winding number N , that occur spontaneously in some magnetic materials. Recent experiments have…
Optical probing of spin fluctuations of a single magnetic atom
L. Besombes, Y. Leger, J. Bernos +4
We analyzed the photoluminescence intermittency generated by a single paramagnetic spin localized in an individual semiconductor quantum dot. The statistics of the photons emitted…
VO: A Strongly Correlated Metal Close to a Mott- Hubbard Transition
F. Rivadulla, J. Fernandez-Rossier, M. Garcia-Hernandez +3
Here we present experimental and computational evidences to support that rock-salt cubic VO is a strongly correlated metal with Non-Fermi-Liquid thermodynamics and an unusually str…
Magnetism in graphene nano-islands
J. Fernandez-Rossier, J. J. Palacios
We study the magnetic properties of nanometer-sized graphene structures with triangular and hexagonal shapes terminated by zig-zag edges. We discuss how the shape of the island, th…
Long-range spin-qubit interaction mediated by microcavity polaritons
G. F. Quinteiro Rosen, J. Fernandez-Rossier, C. Piermarocchi
We study the optically-induced coupling between spins mediated by polaritons in a planar micro-cavity. In the strong coupling regime, the vacuum Rabi splitting introduces anisotrop…
Unconventional Yu-Shiba-Rusinov states in hydrogenated graphene
J. L. Lado, J. Fernandez-Rossier
Conventional in-gap Yu-Shiba-Rusinov states require two ingredients: magnetic atoms and a superconducting host that, in the normal phase, has a finite density of states at the Ferm…
Orbital Magnetization of Quantum Spin Hall Insulator Nanoparticles
P. Potasz, J. Fernandez-Rossier
Both spin and orbital degrees of freedom contribute to the magnetic moment of isolated atoms. However, when inserted in crystals, atomic orbital moments are quenched because of the…
Vacancy induced magnetism in graphene and graphene ribbons
J. J. Palacios, J. Fernandez-Rossier, L. Brey
We address the electronic structure and magnetic properties of vacancies and voids both in graphene and graphene ribbons. Using a mean field Hubbard model, we study the appearance…
Landau Levels in 2D materials using Wannier Hamiltonians obtained by first principles
J. L. Lado, J. Fernandez-Rossier
We present a method to calculate the Landau levels and the corresponding edge states of two dimensional (2D) crystals using as a starting point their electronic structure as obtain…
Real space mapping of topological invariants using artificial neural networks
D. Carvalho, N. A. Garcia-Martinez, J. L. Lado +1
Topological invariants allow to characterize Hamiltonians, predicting the existence of topologically protected in-gap modes. Those invariants can be computed by tracing the evoluti…
Engineering spin exchange in non-bipartite graphene zigzag edges
R. Ortiz, J. L. Lado, M. Melle-Franco +1
The rules that govern spin exchange interaction in pristine graphene nanostructures are constrained by the bipartite character of the lattice, so that the sign of the exchange is d…
Single exciton spectroscopy of single-Mn doped InAs quantum dots
J. van Bree, P. Koenraad, J. Fernandez-Rossier
The optical spectroscopy of a single InAs quantum dot doped with a single Mn atom is studied using a model Hamiltonian that includes the exchange interactions between the spins of…
Berry Phase Estimation in Gate-Based Adiabatic Quantum Simulation
Bruno Murta, G. Catarina, J. Fernandez-Rossier
Gate-based quantum computers can in principle simulate the adiabatic dynamics of a large class of Hamiltonians. Here we consider the cyclic adiabatic evolution of a parameter in th…
Noncollinear magnetic phases and edge states in graphene quantum Hall bars
J. L. Lado, J. Fernandez-Rossier
Application of a perpendicular magnetic field to charge neutral graphene is expected to result in a variety of broken symmetry phases, including antiferromagnetic, canted and ferro…
Edge states in graphene-like systems
J. L. Lado, N. Garcia-Martinez, J. Fernandez-Rossier
The edges of graphene and graphene like systems can host localized states with evanescent wave function with properties radically different from those of the Dirac electrons in bul…