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Gomis-Bresco J.,University of Valencia | Gomis-Bresco J.,Catalan Institute of Nanoscience and Nanotechnology | Munoz-Matutano G.,University of Valencia | Martinez-Pastor J.,University of Valencia | And 5 more authors.
New Journal of Physics | Year: 2011

We model the time-resolved and time-integrated photoluminescence of a single InAs/GaAs quantum dot (QD) using a random population description. We reproduce the joint power dependence of the single QD exciton complexes (neutral exciton, neutral biexciton and charged trions). We use the model to investigate the selective optical pumping phenomenon, a predominance of the negative trion observed when the optical excitation is resonant to a nonintentional impurity level. Our experiments and simulations determine that the negative charge confined in the QD after exciting resonance to the impurity level escapes in 10 ns. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Beltran A.M.,CNRS Toulouse Center for Materials Elaboration and Structural Studies | Sanchez A.M.,University of Warwick | Ripalda J.M.,Institute Microelectronica Of Madrid Cnm | Taboada A.G.,Institute Microelectronica Of Madrid Cnm
Materials Letters | Year: 2011

GaSb incorporation to InAs/GaAs quantum dots is considered for improving the opto-electronic properties of the systems. In order to optimize these properties, the introduction of an intermediate GaAs layer is considered a good approach. In this work, we study the effect of the introduction of a GaAs intermediate layer between InAs quantum dots and a GaSb capping layer on structural and crystalline quality of these heterostructures. As the thickness of the GaAs intermediate layer increases, a reduction of defect density has been observed as well as changes of quantum dots sizes. This approach suggests a promising method to improve the incorporation of Sb to InAs heterostructures. © 2011 Elsevier B.V.


Martinez L.J.,Institute Microelectronica Of Madrid Cnm | Prieto I.,Institute Microelectronica Of Madrid Cnm | Alin B.,Institute Microelectronica Of Madrid Cnm | Gonzalez Y.,Institute Microelectronica Of Madrid Cnm | And 3 more authors.
Optics Express | Year: 2012

The spontaneous emission rate and Purcell factor of selfassembled quantum wires embedded in photonic crystal micro-cavities aremeasured at 80 K by using micro- photoluminescence, under transient and steady state excitation conditions. The Purcell factors fall in the range 1.1 - 2 despite the theoretical prediction of ?15.5 for the figure of merit. We explain this difference by introducing a polarization dependence on the cavity orientation, parallel or perpendicular with respect to the wire axis, plus spectral and spatial detuning factors for the emitters and the cavitymodes, taking in account the finite size of the quantum wires. © 2012 Optical Society of America.


Hamadeh A.,CEA Saclay Nuclear Research Center | D'Allivy Kelly O.,University Paris - Sud | Hahn C.,CEA Saclay Nuclear Research Center | Meley H.,CEA Saclay Nuclear Research Center | And 15 more authors.
Physical Review Letters | Year: 2014

It is demonstrated that the threshold current for damping compensation can be reached in a 5μm diameter YIG(20nm)|Pt(7nm) disk. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of Idc using a magnetic resonance force microscope (MRFM). It is shown that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of 5 depending on the polarity and intensity of an in-plane dc current Idc flowing through the adjacent normal metal with strong spin-orbit interaction. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of ∼3×1011A·m-2, in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime. © 2014 American Physical Society.


Sanchez A.M.,Royal University | Sanchez A.M.,University of Warwick | Beltran A.M.,Royal University | Beanland R.,University of Warwick | And 7 more authors.
Nanotechnology | Year: 2010

The addition of antimony to III-V nanostructures is expected to give greater freedom in bandgap engineering for device applications. One of the main challenges to overcome is the effect of indium and antimony surface segregation. Using several very high resolution analysis techniques we clearly demonstrate blocking of indium incorporation by antimony. Furthermore, indium incorporation resumes when the antimony concentration drops below a critical level. This leads to major differences between nominal and actual structures. © 2010 IOP Publishing Ltd.


PubMed | Grenoble Institute of Technology, University Paris - Sud, Technical University of Madrid, Kazan Federal University and 3 more.
Type: Journal Article | Journal: Physical review letters | Year: 2014

It is demonstrated that the threshold current for damping compensation can be reached in a 5m diameter YIG(20nm)|Pt(7nm) disk. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of I(dc) using a magnetic resonance force microscope (MRFM). It is shown that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of 5 depending on the polarity and intensity of an in-plane dc current I(dc) flowing through the adjacent normal metal with strong spin-orbit interaction. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of 310(11)Am(-2), in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime.


Munoz-Matutano G.,University of Valencia | Royo M.,Jaume I University | Climente J.I.,Jaume I University | Canet-Ferrer J.,University of Valencia | And 8 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We investigate the electronic and optical properties of InAs double quantum dots grown on GaAs (001) and laterally aligned along the [110] crystal direction. The emission spectrum has been investigated as a function of a lateral electric field applied along the quantum dot pair mutual axis. The number of confined electrons can be controlled with the external bias, leading to sharp energy shifts which we use to identify the emission from neutral and charged exciton complexes. Quantum tunneling of these electrons is proposed to explain the reversed ordering of the trion emission lines as compared to that of excitons in our system. © 2011 American Physical Society.


Munoz-Matutano G.,University of Valencia | Suarez I.,Institute Microelectronica Of Madrid Cnm | Canet-Ferrer J.,University of Valencia | Alen B.,Institute Microelectronica Of Madrid Cnm | And 5 more authors.
Journal of Applied Physics | Year: 2012

We have investigated the temperature dependent recombination dynamics in two bimodally distributed InAs self assembled quantum dots samples. A rate equations model has been implemented to investigate the thermally activated carrier escape mechanism which changes from exciton-like to uncorrelated electron and hole pairs as the quantum dot size varies. For the smaller dots, we find a hot exciton thermal escape process. We evaluated the thermal transfer process between quantum dots by the quantum dot density and carrier escape properties of both samples. © 2012 American Institute of Physics.


Munoz M.,Institute Microelectronica Of Madrid Cnm
Nature communications | Year: 2011

Nanofabrication has allowed the development of new concepts such as magnetic logic and race-track memory, both of which are based on the displacement of magnetic domain walls on magnetic nanostripes. One of the issues that has to be solved before devices can meet the market demands is the stochastic behaviour of the domain wall movement in magnetic nanostripes. Here we show that the stochastic nature of the domain wall motion in permalloy nanostripes can be suppressed at very low fields (0.6-2.7 Oe). We also find different field regimes for this stochastic motion that match well with the domain wall propagation modes. The highest pinning probability is found around the precessional mode and, interestingly, it does not depend on the external field in this regime. These results constitute an experimental evidence of the intrinsic nature of the stochastic pinning of domain walls in soft magnetic nanostripes.


Martinez-Criado G.,European Synchrotron Radiation Facility | Homs A.,European Synchrotron Radiation Facility | Alen B.,Institute Microelectronica Of Madrid Cnm | Sans J.A.,Polytechnic University of Valencia | And 5 more authors.
Nano Letters | Year: 2012

Theoretically core-multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier localization phenomena at the hexagon corners by combining synchrotron excited optical luminescence with simultaneous X-ray fluorescence spectroscopy. Applied to single coaxial n-GaN/InGaN multiquantum-well/p-GaN nanowires, our experiment narrows the gap between optical microscopy and high-resolution X-ray imaging and calls for further studies on the underlying mechanisms of optoelectronic nanodevices. © 2012 American Chemical Society.

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