Spin-wave resonances in pelletized powder of bismuth orthoferrite (BiFeO3) were studied in transmission spectroscopy at frequencies of 0.1–0.75 THz and in the temperature range of 300–650 K. A vector network analyzer with frequency extenders was used in co ...

2018

Dirac nodal lines and flat-band surface state in the functional oxide RuO2

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Simon Karl Moser

The efficiency and stability of RuO2 in electrocatalysis has made this material a subject of intense fundamental and industrial interest. The surface functionality is rooted in its electronic and magnetic properties, determined by a complex interplay of la ...

AMER PHYSICAL SOC2018

In Situ Electric Field Skyrmion Creation in Magnetoelectric Cu2OSeO3

Marco Cantoni, Arnaud Magrez, Henrik Moodysson Rønnow, Fabrizio Carbone, Ping Huang, Oleksandr Kriuchkov, Rajeswari Jayaraman

Exploiting additional degrees of freedom in solid-state materials may be the most-promising solution when approaching the quantum limit of Moore's law for the conventional electronic industry. Recently discovered topologically nontrivial spin textures, sky ...

AMER CHEMICAL SOC2018

J1-J2 square lattice antiferromagnetism in the orbitally quenched insulator MoOPO4

Helmuth Berger, László Forró, Arnaud Magrez, Oleg Yazyev, Bálint Náfrádi, Henrik Moodysson Rønnow, Ivica Zivkovic, Peter Babkevich, Lin Yang, Noore Elahi Shaik

We report magnetic and thermodynamic properties of a 4d1 (Mo5+) magnetic insulator MoOPO4 single crystal, which realizes a J1−J2 Heisenberg spin-1/2 model on a stacked square lattice. The specific-heat measurements show a magnetic transition at 16 K which ...

Amer Physical Soc2017

Bulk diffusive relaxation mechanisms in optically excited topological insulators

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Alberto Crepaldi

The possibility to inject spin currents in topological insulators (TIs) by ultrashort optical pulses has stimulated intense studies of their out-of-equilibrium electronic properties. However, a comprehensive description of the electronic relaxation dynamic ...

Amer Physical Soc2017

Elevated transition temperature in Ge doped VO2 thin films

Mihai Adrian Ionescu, Andreas Schueler, Arnaud Magrez, Wolfgang Amadeus Vitale, Anna Krammer, Piotr Mocny

Thermochromic GexV1-xO2+y thin films have been deposited on Si (100) substrates by means of reactive magnetron sputtering. The films were then characterized by Rutherford backscattering spectrometry (RBS), four-point probe electrical resistivity measuremen ...

2017

Strongly bound excitons in anatase TiO2 single crystals and nanoparticles

Helmuth Berger, Marco Grioni, Majed Chergui, Arnaud Magrez, Gerald Auböck, Simon Karl Moser, Edoardo Baldini

Anatase TiO2 is among the most studied materials for light-energy conversion applications, but the nature of its fundamental charge excitations is still unknown. Yet it is crucial to establish whether light absorption creates uncorrelated electron-hole pai ...

Nature Publishing Group2017

Persistence of a surface state arc in the topologically trivial phase of MoTe2

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Oleg Yazyev, Alberto Crepaldi, Gabriel Albert Autes

The prediction of Weyl fermions in the low-temperature noncentrosymmetric 1T' phase of MoTe2 still awaits clear experimental confirmation. Here, we report angle-resolved photoemission (ARPES) data and ab initio calculations that reveal a surface state arc ...

Amer Physical Soc2017

Morphology Engineering: A Route to Highly Reproducible and High Efficiency Perovskite Solar Cells

Michael Graetzel, Arnaud Magrez, Ulf Anders Hagfeldt, Jingshan Luo, Dongqin Bi, Fei Zhang

Despite the rapid increase in the performance of perovskite solar cells (PSC), they still suffer from low lab-to-lab or people-to-people reproducibility. Aiming for a universal condition to high-performance devices, we investigated the morphology evolution ...

Wiley-VCH Verlag Berlin2017

Electronic Phase Separation and Dramatic Inverse Band Renormalization in the Mixed-Valence Cuprate LiCu2O2

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Luca Moreschini, Simon Karl Moser, Gianmarco Gatti

We measured, by angle-resolved photoemission spectroscopy, the electronic structure of LiCu2O2, a mixed-valence cuprate where planes of Cu(I) (3d(10)) ions are sandwiched between layers containing one-dimensional edge-sharing Cu(II) (3d(9)) chains. We find ...

Amer Physical Soc2017

FeOx magnetization enhancing E-coli inactivation by orders of magnitude on Ag-TiO2 nanotubes under sunlight

Juan Kiwi, César Pulgarin, Arnaud Magrez, Ivica Zivkovic, Sami Rtimi, Stefanos Giannakis, Marco Mangayayam

Drastic bacterial enhancement was observed when the Ag(3%)-TiO2 nanotubes were modified with FeOx (3%) magnetic oxide. On bare TiO2- nanotubes a reduction of 0.21og(10)CFU was observed within one hour under simulated low intensity solar light. Under simila ...

Elsevier2017

BiTeCl and BiTeBr: A comparative high-pressure optical study

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Oleg Yazyev, Ana Akrap, Gabriel Albert Autes

We here report a detailed high-pressure infrared transmission study of BiTeCl and BiTeBr. We follow the evolution of two band transitions: the optical excitation beta between two Rashba-split conduction bands, and the absorption. across the band gap. In th ...

Amer Physical Soc2017

Time-resolved ARPES at LACUS: Band Structure and Ultrafast Electron Dynamics of Solids

Helmuth Berger, Philippe Bugnon, Marco Grioni, Majed Chergui, Frank van Mourik, Arnaud Magrez, Christopher Alexander Arrell, Alberto Crepaldi, José Javier Pancracio Ojeda Andara, Gianmarco Gatti, Silvan Dino Marcos Roth

The manipulation of the electronic properties of solids by light is an exciting goal, which requires knowledge of the electronic structure with energy, momentum and temporal resolution. Time- and angle-resolved photoemission spectroscopy (tr-ARPES) is the ...

2017

Cyan titania nanowires: Spectroscopic study of the origin of the self-doping enhanced photocatalytic activity

László Forró, Richard Gaal, Arnaud Magrez, Alla Arakcheeva, Bálint Náfrádi, Xavier Berdat, Jacim Jacimovic, Massimo Spina, Endre Horvath, Laurent Syavoch Bernard, Péter Szirmai

We report a detailed spectroscopic study of Ti3+ self-doped TiO2 nanowires prepared by high temperature annealing of the protonated titanate nanowires (TiONW) in hydrogen atmosphere. Hydrogenation causes a color change from white to cyan and a major increa ...

Elsevier2017

Van der Waals MoS2/VO2 heterostructure junction with tunable rectifier behavior and efficient photoresponse

Igor Stolichnov, Mihai Adrian Ionescu, Andreas Schueler, Olivier Martin, Arnaud Magrez, Chen Yan, Emanuele Andrea Casu, Teodor Rosca, Nicolò Oliva, Anna Krammer

Junctions between n-type semiconductors of different electron affinity show rectification if the junction is abrupt enough. With the advent of 2D materials, we are able to realize thin van der Waals (vdW) heterostructures based on a large diversity of mate ...

Nature Research2017

Titanium oxide aerogel composites

László Forró, Arnaud Magrez, Endre Horvath

The invention relates to titanium oxide aerogels, in particular to titanium oxide binary or ternary (e.g. titanium oxide-carbon) aerogel monoliths possessing ordered meso- and macroporosity. The porous scaffold can be made with or without addition of binde ...

2016

Influence of TiO2 phase composition on the photocatalytic activity of TiO2/MWCNT composites prepared by combined sol-gel/hydrothermal method

László Forró, Arnaud Magrez, Klara Hernadi, Endre Horvath

Titanium dioxide/multiwall carbon nanotube (TiO2/MWCNT) composites were prepared by sol-gel method with hydrolysis of titanium alkoxide precursor followed by crystallization via hydrothermal treatment at different acid concentrations. Transmission electron ...

Elsevier Science Bv2016

Page 3 sur 10