Researchers from the University of Geneva and the University of Manchester have confirmed experimentally the theory of very strong magneto-optical resonance in graphene. The ability to control infrared and terahertz waves using magnetic or electric fields is one of the great challenges in physics that could revolutionise opto-electronics, telecommunications and medical diagnostics. A theory from…
By Prof. Carmine Senatore, UNIGE and Prof. Leonid Rivkin, PSI Since the discovery of superconductivity in 1911, this phenomenon was greeted with high hopes for groundbreaking applications. However, scientists had to face many difficulties to develop these materials in a useful conductor form and yet only six – one alloy, two intermetallic compounds and three ceramic…
by Anna Tamai, University of Geneva based on an article published in Physical Review X Since the seminal work of Landau in the 1950’s, the low-temperature metallic state of materials is generally assumed to be well understood. Yet, when it comes to oxides, even good metals such as the strontium ruthenates continue to hold surprises.…
by Johan Chang, University of Zürich based on an article published in Nature Communications Exposed to pressure, the lattice parameters of a material generally shrink. In turn, the electronic nearest neighbour hopping integral t increases, due to larger orbital overlap. In a Mott insulator this enhancement can trigger a bandwidth-controlled insulator-to-metal transition. Indeed, the ratio, U/t, of…
By Prof. László Forró, EPFL Materials are the linchpin of technological progress. All energy related applications like photovoltaics, fuel cells, thermoelectrics, (harvesting, storing and transmitting) heavily depend on new, more performant materials. Even the success of energy production by nuclear fusion crucially relies on finding compounds that can withstand high doses of irradiation. Information technologies are…
by Björn Wehinger, UNIGE and PSI based on an article published in Physical Review Letters Quantum magnets have evolved over the past decade into systems of large interest in fundamental and, increasingly, in applied physics. Their exceptional properties, including non-magnetic ground states, fractionalised excitations and topological order, have become candidate resources for quantum information and computing. Application in spintronic…
by Jan Hugo Dil, EPFL based on an article published in Physical Review X The control of the electron spin in functional materials by an external electric field is a key issue for spintronic devices. Because the spin is not directly influenced by a realistic electric field, the coupling has to be indirect and thus especially…
Physicists from Rice University and the University of Geneva have verified a key prediction from a 55-year-old theory about one-dimensional electronics that is increasingly relevant thanks to Silicon Valley’s inexorable quest for miniaturization. “Chipmakers have been shrinking feature sizes on microchips for decades, and device physicists are now exploring the use of nanowires and nanotubes…
Predicting the behaviour of electrons in a material is not easily done. Physicists from the University of Geneva (UNIGE), ETH Zurich and EPFL replaced the electrons with ultra-cold neutral lithium atoms that they had circulated in a one-dimensional quantum tube. The scientists were then able to confirm an unusual state of matter that retains its…
Scilight from AIP Publishing is talking about a recent publication of Hugo Meley and coworkers in APL Materials. Moving from discovering physical properties to the ability to tailor them requires precise understanding and mastery of materials fabrication. This study unveils how the substrate affects the growth of crystalline vanadate thin films and the arrangement of their…
A unique cryogenic scanning near-field optical microscope (cryo-SNOM) has been installed at the DQMP and is now able to demonstrate the first promising results. In contrast to the conventional optical microscopes, in this system the sample is probed by the so called evanescent electromagnetic waves, which are emitted and detected by an ultrasharp metallized tip…
by Christophe Berthod, Ivan Maggio-Aprile, Christoph Renner, Department of Quantum Matter Physics, University of Geneva based on an article published in Physical Review Letters Copper oxide superconductors were the first to be found superconducting above liquid nitrogen temperature in the mid-1980s, thus shattering through the maximum critical temperature of 35K foreseen by theorists. The mechanism enabling…
by Daniel Mazzone, Paul Scherrer Institut based on an article published in Physical Review Letters Most superconducting condensates are accurately described within the scope of the BCS-theory (Bardeen-Cooper-Schrieffer), where electrons are bound together via virtual phonons. They are in strong contrast to so-called unconventional superconductors, in which the pairing mechanism is still unclear but thought to arise from magnetic…
In a superconductor, the electrons experience very peculiar interactions whose most surprising effect is a total loss of electrical resistance. These materials are therefore promising for future applications, especially since some of them work at the temperature of liquid nitrogen. The mechanism behind these exceptional properties remains mysterious, though. Studying these materials when they are…
by Björn Wehinger, Department of Quantum Matter Physics, University of Geneva based on an article published in Physical Review Letters Physicists from the University of Geneva and the European Synchrotron discovered how to obtain the full elasticity tensor from a single crystal diffraction experiment. Measurements of thermal diffuse scattering revealed that the complete set of…
by Mickaël Morin and Marisa Medarde, Paul Scherrer Institut based on an article published in Nature Communications In the past years, magnetism-driven ferroelectricity has been reported in a number of frustrated magnets with spiral magnetic orders. Such materials are of high current interest due to their potential for spintronics and low-power magnetoelectric devices. However, their low…
The terahertz waves span frequency ranges between the infrared spectrum (used, for example, for night vision) and gigahertz waves (which find their application, among other, in Wi-Fi connections). Terahertz waves allow for the detection of materials that are undetectable at other frequencies. However, the use of these waves is severely limited by the absence of…
by Sebastian Manz and Manfred Fiebig, ETH Zürich based on an article published in Nature Photonics Antiferromagnetism is magnetic order, yet without a macroscopic magnetization as in iron. The absence of the field has interesting technological potential, but it also makes the antiferromagnetic state harder to control and set in a certain direction.…
by Tomáš Bzdušek, Department of Physics, ETH Zürich based on an article published in Nature The microscopic distinction between ordinary insulators and metals is understood since the early years of quantum mechanics by the so-called band theory. Semimetals form a natural boundary between the two, and they attracted much attention in recent years due to their unusual…
by Luc Patthey, PSI (Paul Scherrer Institut) The new Swiss Free Electron Laser facility SwissFEL is a unique light source which will provide new opportunities for cutting-edge research, and aims at providing solutions to important scientific and technological challenges facing modern society in the fields of Matter and Materials, Energy and the Environment, and Human Health. SwissFEL…
Marta Gibert receives the Swiss Physical Society (SPS) Prize sponsored by IBM for her research on magnetic coupling at oxide interfaces, particularly in the interface engineering of heterostructures combining nickelates and manganites. The results led to the publications: “Exchange bias in LaNiO3–LaMnO3 superlattices“, M. Gibert, et al., Nature Materials 11, 195 (2012). “Interfacial Control of Magnetic Properties…
Some materials hold surprising — and possibly useful — properties: Neodymium nickel oxide is either a metal or an insulator, depending on temperature. This characteristic makes the material a potential candidate for transistors in modern electronic devices. To understand how neodymium nickel oxide makes the transition from metal to insulator and vice versa, researchers at…
Crystalline solids have particlelike, low-energy excitations — so-called quasiparticles — that describe collective states of many electrons interacting with the atomic nuclei. In 2015, scientists predicted the existence of an exotic new quasiparticle, dubbed a type-II Weyl fermion, that breaks the Lorentz invariance of special relativity and has no direct analog in the standard model…
Superconductivity with a high critical temperature (high Tc) continues to present a theoretical mystery. While this phenomenon is experimentally well established, no scientist has managed to explain its mechanism. In the late 90’s, the British physicist Anthony Leggett proposed a scenario based on the Coulomb energy. Today, researchers at the University of Geneva (UNIGE), Switzerland,…
By Pieter J. de Visser and Alexey B. Kuzmenko, Department of Quantum Matter Physics, UNIGE After an article published in Physical Review Letters In electronics and photonics there is a continuous quest for novel ways to excite and manipulate electrons in materials due to interaction with light. A recent development is valleytronics, in which the…
An international collaboration involving researchers from the University of Geneva, and colleagues from England, Spain, France and Luxembourg has demonstrated that destabilising the spontaneous polarisation of a special class of materials known as ferroelectrics gives rise to the phenomenon of negative capacitance that could one day lead to transistors with reduced power consumption. This research…
The unusual electronic properties of some superconducting materials permit lossless and dense electrical currents at very low temperatures, even in high magnetic fields. Conductors made of these materials are thus ideal for winding coils to generate very high magnetic fields, which are essential for a number of applications like magnetic medical imaging, magnetic resonance spectroscopy…
by Vladimir N. Strocov, Swiss Light Source, Paul Scherrer Institute Claudia Cancellieri, Materials Theory, EMPA / ETH Zurich Ulrich Aschauer, Chemistry and Biochemistry, University of Bern based on an article published in Nature Communications Press release Computers and other electronic devices account for a substantial portion of worldwide energy use. With today’s technologies, it is not possible to…
Interlayer coupling through a dimensionality-induced magnetic state by Marta Gibert and Jean-Marc Triscone Department of Quantum Matter Physics, UNIGE Contact: Prof. Jean-Marc Triscone (Tél. +41 22 379 62 18) based on an article published in Nature Communication Press release French/English Every day, new technologies require more precision in the intrinsic properties of the materials used. To meet…
A microchip that filters out unwanted radiation with the help of graphene has been developed by scientists from the EPFL and tested by researchers of the University of Geneva (UNIGE). The invention could be used in future devices to transmit wireless data ten times faster. EPFL and UNIGE scientists, have developed a microchip using graphene…
Superconducting materials have the characteristic of letting an electric current flow without resistance. The study of superconductors with a high critical temperature discovered in the 1980s remains a very attractive research subject for physicists. Indeed, many experimental observations still lack an adequate theoretical description. Researchers from the University of Geneva (UNIGE) in Switzerland and the…
by Thierry Giamarchi, Department of Quantum Matter Physics, UNIGE Jean-Philippe Brantut, Institute for Quantum Electronics, Quantum optics group, ETH Zürich Tilman Esslinger, Institute for Quantum Electronics, Quantum optics group, ETH Zürich based on an article published in Science Work of physicists at the University of Geneva (UNIGE) and the Swiss Federal Institute of Technology in Zurich (ETHZ), in which they connected two materials with…
By Christian E. Matt Swiss Light Source, Paul Scherrer Institute & Laboratory for Solid State Physics, ETHZ Claudia G. Fatuzzo, Institute for Condensed Matter Physics, EPFL Johan Chang, Physik-Institut, Universität Zürich based on an article published in Physical Review B For the past 30 years, high-temperature superconductivity presents itself as one of the most…
by Alberto Morpurgo, Department of Quantum Matter Physics, UNIGE based on an article published in Nature Communication Topological insulators are a new class of materials that are insulating in the bulk but have conducting boundaries (surfaces or edges). Their discovery has been made by analyzing theoretically the influence of spin-orbit interaction on the properties of graphene –…
The Geneva team of Prof. Jean-Marc Triscone is well known for the high quality oxide materials that they can synthesize in thin film form with nanoscale control. Of great interest is the family of so-called nickelates. These materials are metallic at high temperature but become insulating and magnetic at low temperature – they display a…
Summary Over the past decade, interfaces between oxide materials have been intensely studied, due to the powerful and often unexpected properties they can exhibit. New research using angle-resolved photoemission is revealing that another kind of “interface” – an oxide material’s surface – can be just as fascinating. Investigating a recently discovered surface state on SrTiO3,…
Summary It is known for a long time that chameleons darken their skin through a process of melanin migration from the deep to the top layers of the dermis. When adult males are confronting a rival or a female, they rapidly switch between bright colors, changing from green to yellow, for example. It was…
An Italian-Swiss study just published in ‘Nature Communications’ reveals how some artificial materials composed of different oxides are able to convert heat into electricity with unprecedented efficiency. This work uncovered by researchers from the Universities of Genoa and Geneva, in collaboration with the Italian National Centre for Research (Cnr) opens the door to the use…
The Graphene Flagship, with a budget of €1 billion over a period of ten years, lays out a science and technology roadmap targeting research areas designed to take graphene and related 2d materials from academic laboratories into society. It comprises the activities of 142 academic and industrial partners in 23 countries, amongst which there are…
Could graphene turn light to electricity? Scientists have shown that graphene can convert a single photon into multiple electrons, showing much promise for future photovoltaic devices. Graphene is a material that has gathered tremendous popularity in recent years, due to its extraordinary strength and light weight. It can be generated by literally peeling it off…
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