A5010815252- Rare-earth and actinide compounds
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Nuclear Materials and Properties
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Thermodynamic and Structural Properties of Metals and Alloys
- Organic and Molecular Conductors Research
- Solid-state spectroscopy and crystallography
- Particle Detector Development and Performance
- Semiconductor materials and devices
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Ferroelectric and Negative Capacitance Devices
- Nonlinear Dynamics and Pattern Formation
- Computational Physics and Python Applications
- Advanced Materials Characterization Techniques
- Magnetism in coordination complexes
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- Fusion materials and technologies
University of Geneva
2015-2022
European Organization for Nuclear Research
2022
Centre National de la Recherche Scientifique
2012-2017
Laboratoire National des Champs Magnétiques Intenses
2012-2017
Université Toulouse III - Paul Sabatier
2012-2017
Université Grenoble Alpes
2017
Technical University of Munich
2017
Heinz Maier-Leibnitz Zentrum
2017
Université Joseph Fourier
2012
We report angle resolved photoemission experiments on the electron doped Heisenberg antiferromagnet (Sr(1-x)La(x))(2)IrO(4). For a doping level of x=0.05, we find an unusual metallic state with coherent nodal excitations and antinodal pseudogap bearing strong similarities underdoped cuprates. This emerges from rapid collapse Mott gap resulting in large underlying Fermi surface that is backfolded by (π,π) reciprocal lattice vector which attribute to intrinsic structural distortion Sr(2)IrO(4).
Abstract We report the influence on superconducting critical temperature T c in doped SrTiO 3 of substitution natural 16 O atoms by heavier isotope 18 O. observe that for a wide range doping this causes strong (~50%) enhancement . Also magnetic field H 2 is increased factor ~2. Such impact and , with sign opposite to conventional superconductors, unprecedented. The observed effect could be consequence coupling electrons lattice vibrations (phonons), notion which finds support numerous...
Doped strontium titanate ${\mathrm{SrTiO}}_{3}$ (STO) is one of the most dilute superconductors known today. The fact that superconductivity occurs at very low carrier concentrations two reasons pairing mechanism not yet understood, other being role played by proximity to a ferroelectric instability. In undoped STO, order can in be stabilized substituting $^{16}\mathrm{O}$ with its heavier isotope $^{18}\mathrm{O}$. Here, we explore superconducting properties doped and isotope-substituted...
We report magnetization and magnetoresistivity measurements on the isostructural ferromagnetic superconductors UCoGe URhGe in magnetic fields up to 60 T temperatures from 1.5 80 K. At low temperature, a moment polarization field ${\ensuremath{\mu}}_{0}\mathbf{H}\ensuremath{\parallel}\mathbf{b}$ of around 50 leads well-defined anomalies both magnetoresistivity. These vanish higher than 30--40 K, where maxima susceptibility field-induced variation are found. A comparison is made between URhGe,...
URu${}_{2}$Si${}_{2}$ is surely one of the most mysterious heavy-fermion compounds. Despite more than 20 years experimental and theoretical works, order parameter transition at ${T}_{0}=17.5$ K still unknown. The state below ${T}_{0}$ called ``hidden-order phase,'' stakes are to identify energy scales driving system this phase. We present new magnetoresistivity magnetization measurements performed on very-high-quality single crystals in pulsed magnetic fields up 60 T. show that hidden-order...
We report neutron diffraction measurements on $\mathrm{U}({\mathrm{Ru}}_{0.96}{\mathrm{Rh}}_{0.04}{)}_{2}{\mathrm{Si}}_{2}$ single crystal under pulsed high magnetic fields up to 30 T applied along the tetragonal $c$ axis. The high-field experiments revealed that field-induced phase II above 26 corresponds a commensurate up-up-down ferrimagnetic structure characterized by wave vector $\mathbit{q}=(2/3,0,0)$ with moments parallel axis, which naturally explains one-third magnetization plateau...
Despite almost 40 years of research, the origin heavy-fermion superconductivity is still strongly debated. Especially, pressure-induced enhancement in CeCu$_2$Si$_2$ away from magnetic breakdown not sufficiently taken into consideration. As recently reported and several related compounds, optimal occurs at pressure a valence crossover, which arises virtual critical end point negative temperature $T_{\rm cr}$. In this context, we did meticulous analysis vast set top-quality high-pressure...
SrTiO3 is an insulating material which, using chemical doping, pressure, strain or isotope substitution, can be turned into a ferroelectric superconductor. The itself, and the two aforementioned phenomena, have been subjects of intensive research Karl Alex Müller source inspiration, among other things, for his Nobel prize-winning on high temperature superconductivity. An intriguing outstanding question whether occurrence ferroelectricity superconductivity in same just coincidence, deeper...
We present measurements of the resistivity $\rho_{x,x}$ URu2Si2 high-quality single crystals in pulsed high magnetic fields up to 81~T at a temperature 1.4~K and 60~T temperatures down 100~mK. For field \textbf{H} applied along easy-axis \textbf{c}, strong sample-dependence low-temperature hidden-order phase is attributed carrier mobility. The interplay between orbital properties emphasized by angle-dependence diagram, where transition crossover related Fermi surface follow...
De Haas-van Alphen oscillations of the organic metal $\theta$-(ET)$_4$ZnBr$_4$(C$_6$H$_4$Cl$_2$) are studied in pulsed magnetic fields up to 81 T. The long decay time pulse allows determining reliable field-dependent amplitudes Fourier components with frequencies several kiloteslas. spectrum is agreement model a linear chain coupled orbits. In this model, all observed combinations frequency linked basic orbit $\alpha$ and magnetic-breakdown $\beta$.
We present accurate electrical resistivity measurements along the two principle crystallographic axes of pressure-induced heavy-fermion superconductor ${\mathrm{CeRhIn}}_{5}$ up to 5.63 GPa. For both directions, a valence crossover line is identified in $p\text{\ensuremath{-}}T$ plane and extrapolation this zero temperature coincides with collapse magnetic ordering temperature. Furthermore, it found that phase diagram region very similar ${\mathrm{CeCu}}_{2}{\mathrm{Si}}_{2}$. These results...
We studied the in-plane dynamic and static charge conductivity of electron doped ${\mathrm{Sr}}_{2}{\mathrm{IrO}}_{4}$ using optical spectroscopy DC transport measurements. The indicates that pristine material is an indirect semiconductor with a direct Mott gap 0.55 eV. Upon substitution $2%$ La per formula unit suppressed except in small fraction (15%) where survives, overall remains insulating. Instead zero energy mode (or Drude peak) we observe soft collective (SCM) broad maximum at...
We present measurements of the magnetoresistivity RHOxx URu2Si2 single crystals in high magnetic fields up to 60 T and at temperatures from 1.4 K 40 K. Different orientations field have been investigated permitting follow dependence on Q all phase transitions crossovers, where is angle between easy-axis c. find out that crossovers a simple 1/cos(Q) -law, indicating they are controlled by projection c-axis.
${\mathrm{CeAu}}_{2}{\mathrm{Si}}_{2}$ is a newly discovered pressure-induced heavy fermion superconductor, which shows very unusual interplay between superconductivity and magnetism under pressure. Here we compare the results of high-pressure measurements on single-crystalline samples with different levels disorder. It found that while magnetic properties are essentially sample independent, rapidly suppressed when residual resistivity increases. We show depression bulk ${T}_{\mathrm{c}}$...
We report a combined study of in-plane resistivity and thermopower the pressure-induced heavy-fermion superconductor ${\mathrm{CeAu}}_{2}{\mathrm{Si}}_{2}$ up to 27.8 GPa. It is found that follows scaling behavior in $T/{T}^{*}$ almost magnetic critical pressure ${p}_{\mathrm{c}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}22$ By comparing with results, we show magnitude characteristic temperature dependence this range are governed by Kondo coupling crystal-field splitting, respectively. Below...
The pressure-temperature-phase diagram of the new heavy-fermion superconductor CeAu$_2$Si$_2$ is markedly different from those studied previously. Indeed, superconductivity emerges, not on verge, but deep inside magnetic phase. In this context, we have carried out ac-calorimetry, resistivity and thermoelectric power measurements a CeAu$_2$Si$_2$-single crystal under high-pressure. principal novelties experiment are observation transition line, presumably structure rearrangement at...
We report the influence on superconducting critical temperature $T_c$ in doped SrTiO$_3$ of substitution natural $^{16}$O atoms by heavier isotope $^{18}$O. observe that for a wide range doping this causes strong ($\sim 50 \%$) enhancement $T_c$. Also magnetic field $H_{c2}$ is increased factor $\sim 2$. Such impact and $H_{c2}$, with sign opposite to conventional superconductors, unprecedented. The observed effect could be consequence coupling electrons lattice vibrations (phonons), notion...
The discovery of the Higgs boson by ATLAS and CMS collaborations in 2012 concluded longest search for a particle history physics was based on largest most complex experiments ever conducted, involving thousands scientists engineers from around world. It provided crucial evidence theory developed 1960s that describes existence invisible Brout–Englert–Higgs field effects this mass elementary particles. After discovery, work theoretical prediction awarded Nobel Prize Physics 2013. This provides...
Nanoscale channels realized at the conducting interface between ${\mathrm{LaAlO}}_{3}$ and ${\mathrm{SrTiO}}_{3}$ provide a perfect playground to explore effect of dimensionality on electronic properties complex oxides. Here we compare electric transport devices using atomic force microscope-writing technique conventional photolithography. We find that lateral size paths has strong their behavior low temperature. observe crossover from metallic an insulating regime occurring about 50 K for...
The features of the magnetic $(H,T)$ phase diagram ${\mathrm{CeCu}}_{2}{\mathrm{Ge}}_{2}$ are similar to those superconducting ${\mathrm{CeCu}}_{2}{\mathrm{Si}}_{2}$, but nature these phases and transitions is still controversial. For we present results on electrical transport, thermodynamic measurements (magnetization, magnetostriction), elastic neutron diffraction for fields up 15 T parallel [110] direction. Two AF1, AF2 a third, yet unidentified ferrimagnetic AF3 exist below...
Abstract This paper aims to provide a basis for teachers interested in bringing modern particle detectors into their classrooms. In particular, it gives an overview of the basic principles detectors, linking them concepts that are already part curriculum. addition, explains essential detector components present all systems, and how information they leads identification. By highlighting relevant classroom resources, this serves as valuable guide seeking include physics teaching, set within...