The 2016 oxide electronic materials and oxide interfaces roadmap.

Written by Gervasi Herranz on . Posted in Latest Results

M Lorenz, M S Ramachandra Rao, T Venkatesan, E Fortunato, P Barquinha, R Branquinho, D Salgueiro, R Martins, E Carlos, A Liu, F K Shan, M Grundmann, H Boschker, J Mukherjee, M Priyadarshini,N DasGupta, D J Rogers, F H Teherani, E V Sandana, P Bove, K Rietwyk, A Zaban, A Veziridis,A Weidenkaff, M Muralidhar, M Murakami, S Abel, J Fompeyrine, J Zuniga-Perez, R Ramesh,N A Spaldin, S Ostanin, V Borisov, I Mertig, V Lazenka, G Srinivasan, W Prellier, M Uchida,M Kawasaki, R Pentcheva, P Gegenwart, F Miletto Granozio, J Fontcuberta and N Pryds.

J. Phys. D: Appl. Phys. 49 (2016) 433001 (53pp). DOI: 10.1088/0022-3727/49/43/433001

Giant Optical Polarization Rotation Induced by Spin-Orbit Coupling in Polarons

Written by Gervasi Herranz on . Posted in Latest Results

In this work, published in Physical Review Letters, we demonstrate that the polarization of light is changed dramatically when its energy resonates with the polaron-hopping energy of self-trapped electrons.  In the presence of spin-orbit coupling, the self-trapped hopping electron may reverse its spin producing a large gyrotropic effect, which is observed close to room temperature. The effect is observed in La2∕3Ca1∕3MnO3 thin films and, plausibly, should be present in other manganites.

Since straining this kind of materials can change the polaron concentration, our finding suggests a route to mechanical or electro-mechanical control of the magneto-optical effect, paving  the way to unconventional magnetoelectric effects.

This work has been highlighted with a Synopsis on the Physics website:

http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.117.026401

 

 

The Shortening of MWNT-SPION Hybrids by Steam Treatment Improves Their Magnetic Resonance Imaging Properties In Vitro and In Vivo.

Written by Gervasi Herranz on . Posted in Latest Results

Laura Cabana, Maxime Bourgognon, Julie T.-W. Wang, Andrea Protti, Rebecca Klippstein, Rafael T. M. de Rosales, Ajay M. Shah, Josep Fontcuberta, Ester Tobías-Rossell, Jane K. Sosabowski, Khuloud T. Al-Jamal,* and Gerard Tobias*

Small 2016, 12, No. 21, 2893–2905. DOI: 10.1002/smll.201502721

large roomtemperature

Large Room-Temperature Electroresistance in Dual-Modulated Ferroelectric Tunnel Barriers

Written by jags on . Posted in Latest Results

Greta Radaelli , Diego Gutiérrez , Florencio Sánchez , Riccardo Bertacco , Massimiliano Stengel , and Josep Fontcuberta
Adv. Mater. 2015, DOI: 10.1002/adma.201405117

Pt/BaTiO3/La0.7Sr0.3MnO3 tunnel junctions.

It is demonstrated that reversing the polarization direction of a ferroelectric barrier in a tunnel junction leads to a change of junction conductance and capacitance, with concomitant variations on the barrier height and effective thickness, both contributing to produce larger electroresistance

Electrons moving in 2D: symmetry matters

Written by jags on . Posted in Latest Results

The development of today’s electronics is reaching fundamental limits and novel concepts and materials are researched to achieve ever faster and more efficient electronic devices. In this regard, oxides are well positioned, as they display a fascinating complexity of electronic phases –not present in conventional semiconductors–that may open new pathways.

The interface between LaAlO3 and SrTiO3 is the oxide quantum well (QW) par excellence, where superconductivity and magnetism emerge. In LaAlO3/SrTiO3 QWs electrons move in two dimensions forming a two-dimensional electron gas (2DEG, Box a). However, not all the electrons reside in the same QW subband (Box b) and, indeed, they behave differently depending on which orbital are they occupying. We demonstrate that the symmetry of the conduction band inside the QWs can be selected, so that the properties of electrons vary largely. In particular, we show that in the superconductive state Cooper pairs do not bind in the same way either when we change the number of electrons in the 2DEG by electric fields (Box a) or when the direction of confinement is changed (Box b). We also show that choosing the confinement plane allows manipulating the spin-dependent transport in these QWs.

Our work opens a groundbreaking route to manipulate selectively electrons in two dimensions. See more @ G. Herranz at al., Engineering two-dimensional superconductivity and Rashba spin–orbit coupling in LaAlO3/SrTiO3 quantum wells by selective orbital occupancy, Nature Communications 2014, doi:10.1038/ncomms7028. 

Imagen1

Magneto-optic responses boosted by plasmons

Written by jags on . Posted in Latest Results

Imagen1

 

OndřejVlašín, OanaPascu, Anna Roig, and GervasiHerranz

Phys. Rev. Applied 2, 054003 (2014)  DOI: http://dx.doi.org/10.1103/PhysRevApplied.2.054003

 

We show that very diluted dispersions of ferromagnetic metal nanoparticles in diamagnetic hosts show a large, linear response under an applied magnetic field, which is of interest for emerging applications in sensing, integrated optical communications, and magneto-optical current transformers and transducers.  We present also a theory that describes accurately these results and that can be further extended to describe the optical properties of e.g., metal inclusions in polymers or glasses.

prl113

Two-Dimensional Electron Gases at LaAlO3/SrTiO3 Interfaces: Orbital Symmetry and Hierarchy Engineered by Crystal Orientation

Written by jags on . Posted in Latest Results

prl113

 

D. Pesquera, M. Scigaj, P. Gargiani, A. Barla, J. Herrero-Martín, E. Pellegrin, S. M. Valvidares, J. Gázquez, M. Varela, N. Dix, J. Fontcuberta, F. Sánchez, and G. Herranz

Phys. Rev. Lett. 113, 156802 (2014), DOI: http://dx.doi.org/10.1103/PhysRevLett.113.156802

 

Quantum wells at the LaAlO3/SrTiO3 interface with tunable electron states

Quantum wells with d-electrons at the LaAlO3(LAO)/SrTiO3(STO) interface exhibit physical properties, such as superconductivity or magnetism, unseen in conventional semiconductors (Si, Ge, GaAs, …). We have demonstrated that the symmetry of the conduction band inside the QWs can be selected at whish. This opens up novel perspectives to manipulate the electronic properties of QWs at the LAO/STO interface.

apl2014

Spin Hall magnetoresistance at Pt/CoFe2O4 interfaces and texture effects

Written by jags on . Posted in Latest Results

apl2014

 

MirenIsasa, Amilcar Bedoya-Pinto, Saül Vélez, Federico Golmar, Florencio Sánchez, Luis E. Hueso, Josep Fontcuberta, and Fèlix Casanova
Applied Physics Letters 105, 142402 (2014) 

 SPINTRONICS WITH NON-MAGNETIC MATERIALS. The neighborhood   makes all difference

It has been discovered that  electric resistance of a nonmagnetic metal (Pt in our case) is depending on  magnetization state of neighboring insulating ferromagnetic layer, namely on the atomic planes forming the interface and their crystallographic orientation.

Electric transport through nanometric CoFe2O4 thin films investigated by conducting atomic force microscopy

Written by jags on . Posted in Latest Results

M. Foerster, D.F. Gutierrez, J. M. Rebled, E. Arbelo, F. Rigato, M. Jourdan, F. Peiró, J. Fontcuberta

J. Appl. Phys. 111, 013904 (2012)

http://dx.doi.org/10.1063/1.3672839

A systematic study of electric transport through thin (2–8 nm) CoFe2O4 films deposited on epitaxial

SrRuO3 bottom electrodes was performed by conducting atomic force microscopy (CAFM).

Experimental procedures to investigate transport through thin insulating films by CAFM are critically

revised, and the potential of CoFe2O4 films for the use as spin-filtering barriers is assessed. It is concluded that, at room-temperature, a non-tunnel channel significantly contributes to the electric transport, thuslimiting the spin-filtering efficiency.