Publications associées à Resonating valence bond theory

Ab Initio Electron-Phonon Interactions in Correlated Electron Systems

Nicola Marzari, Iurii Timrov, Matteo Cococcioni, Andrea Floris

Electron-phonon (e-ph) interactions are pervasive in condensed matter, governing phenomena such as transport, superconductivity, charge-density waves, polarons, and metal-insulator transitions. First-principles approaches enable accurate calculations of e- ...

AMER PHYSICAL SOC2021

Tunneling processes through magnetic impurities on superconducting surfaces: Yu-Shiba-Rusinov states and the Josephson effect

Haonan Huang

Magnetic impurities generate a wealth of phenomena on surfaces. On metals, conducting electrons screen the magnetic moment giving rise to the Kondo effect. On superconductors, the Yu-Shiba-Rusinov (YSR) states emerge inside the superconducting gap due to t ...

EPFL2021

From quantum spin chains to square lattice Heisenberg anti-ferromagnets

Noore Elahi Shaik

This thesis presents a theoretical study of the Heisenberg model on a two dimensional lattice with asymmetric couplings along x and y directions. By gradually varying the coupling along y-direction we traverse the 1D, quasi 1D and 2D domains of this model. ...

EPFL2019

Kondo lattice excitation observed using resonant inelastic x-ray scattering at the YbM5 edge

Marco Grioni, Marco Guarise, Thorsten Schmitt

We present a study of the resonant inelastic scattering response of YbInCu4 excited at the tender YbM5 x-ray edge. In the high-temperature, paramagnetic phase, we observe a multiplet structure which can be understood at an ionic level. Upon cooling through ...

AMER PHYSICAL SOC2018

Spectroscopic Studies of the Electronic Structure in Layered Cuprates and Ruthenates

Claudia Giuseppina Fatuzzo

In materials where electrons interact strongly, a number of exotic and exciting phenomena arise. The mechanisms at the base of many of these phenomena remain debated, as strongly correlated electron physics represents one of the biggest challenges for mode ...

EPFL2017

Non-Zhang-Rice Singlet Character of the First Ionization State of T-CuO

Simon Karl Moser

We argue that tetragonal CuO (T-CuO) has the potential to finally settle long-standing modeling issues for cuprate physics. We compare the one-hole quasiparticle (qp) dispersion of T-CuO to that of cuprates, in the framework of the strongly correlated (U-d ...

Amer Physical Soc2016

Spin and orbital disordering by hole doping in Pr1-xCaxVO3

Philip Pattison

High-resolution powder x-ray diffraction and single-crystal neutron diffraction were used to investigate the crystal structure and magnetic ordering of the compound Pr1-xCax VO3 (0

Amer Physical Soc2016

Magnons in tetragonal CuO

Henrik Moodysson Rønnow, Frédéric Mila, Marco Grioni, Simon Karl Moser, Thorsten Schmitt, Bastien Dalla Piazza, Sara Fatale, Noore Elahi Shaik

We investigate by resonant inelastic x-ray scattering the magnetic excitations in thin films of tetragonal CuO. We identify a spin wave excitation, dispersing on two cupratelike antiferromagnetic sublattices. Its energy at the boundary of the Brillouin zon ...

2015

Magnetic field, frequency and temperature dependence of complex conductance of ultrathin La1.65Sr0.45CuO4/La2CuO4 films and the organic superconductors kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic, Xi He

We used atomic-layer molecular beam epitaxy (ALL-MBE) to synthesize bilayer films of a cuprate metal (La1.65Sr0.45CuO4, LSCO) and a cuprate insulator (La2CuO4, LCO), in which interface superconductivity occurs in a layer that is just one-half unit cell thi ...

World Scientific Publ Co Pte Ltd2015

Optical properties of V2O3 in its whole phase diagram

Vanadium sesquioxide V2O3 is considered a textbook example of Mott-Hubbard physics. In this paper, we present an extended optical study of its whole temperature/doping phase diagram as obtained by doping the pure material with M = Cr or Ti atoms (V1-x M-x) ...

Amer Physical Soc2015

Sc2Ga2CuO7: A possible quantum spin liquid near the percolation threshold

Henrik Moodysson Rønnow, Paul Gregory Freeman

Sc2Ga2CuO7 (SGCO) crystallizes in a hexagonal structure (space group: P63/mmc), which can be seen as an alternating stacking of single and double triangular layers. Combining neutron, x-ray, and resonant x-ray diffraction, we establish that the single tria ...

2015

Scanning Tunneling Microscopy using Superconducting Tips to Probe Absolute Spin Polarization

Matthias Alexander Eltschka

The interplay of superconductivity and magnetism is investigated for systems with dimensions ranging from the mesoscopic to the atomic scale by scanning tunneling microscopy (STM) at millikelvin temperatures and by numerical calculations. Based on geometri ...

EPFL2015

Glassy dynamics in the low-temperature inhomogeneous ferromagnetic phase of the quantum spin ice Yb2Sn2O7

Ivica Zivkovic, Julian Piatek

Here we present a detailed muon spin relaxation (mu SR), neutron diffraction, and ac-susceptibility study of Yb2Sn2O7 that shows that despite the onset of ferromagnetic long-range order at T-c approximate to 0.140 K, the low-temperature phase of this mater ...

Amer Physical Soc2014

The nature of the quasiparticles in two benchmark transition metal oxides : a spectroscopic study of anatase TiO₂ and tetragonal CuO

Simon Karl Moser

Transition metal oxides (TMOs) are emerging strong players in many domains, ranging from superconductivity, to microelectronics to spintronics to light harvesting for photovoltaics. Beyond their non-toxicity, low corrosiveness and low price, they exhibit a ...

EPFL2014

Theories of Experimentally Observed Excitation Spectra of Square Lattice Antiferromagnets

Bastien Dalla Piazza

The first part of this thesis presents the theoretical study of an anomaly of unknown origin in the excitation spectrum of the Quantumspin-1/2 Heisenberg Square lattice Anti-Ferromagnet. The anomaly manifests itself in Inelastic Neutron Scattering data for ...

EPFL2014

Evolution from a Nodeless Gap to d(x2-y2)-Wave in Underdoped La2-xSrxCuO4

Joël Mesot, Johan Juul Chang, Elia Razzoli

Using angle-resolved photoemission spectroscopy (ARPES), it is revealed that the low-energy electronic excitation spectra of highly underdoped superconducting and nonsuperconducting La2-xSrxCuO4 cuprates are gapped along the entire underlying Fermi surface ...

Amer Physical Soc2013

Band structure effects on the superconductivity in Hubbard models

Ronny Thomale

We study the influence of the band structure on the symmetry and superconducting transition temperature in the (solvable) weak-coupling limit of the repulsive Hubbard model. Among other results we find that (1) as a function of increasing nematicity, start ...

Amer Physical Soc2013

The Interplay Between Structural and Electronic Degrees of Freedom in Superconductors

Mathieu Julien Gino Cottet

More than one hundred years after the discovery of superconductivity in Leiden, the intriguing physics of several unconventional classes of superconductors continue to fascinate and challenge scientists from all over the world. The majority of these compou ...

EPFL2013

Spin-Orbital Quantum Liquid on the Honeycomb Lattice

Frédéric Mila, Karlo Penc, Miklos Lajko

The main characteristic of Mott insulators, as compared to band insulators, is to host low-energy spin fluctuations. In addition, Mott insulators often possess orbital degrees of freedom when crystal-field levels are partially filled. While in the majority ...

American Physical Society2012

Vison excitations in near-critical quantum dimer models

Dmitri Ivanov

We study vison excitations in a quantum dimer model interpolating between the Rokhsar-Kivelson models on the square and triangular lattices. In the square-lattice case, the model is known to be critical and characterized by U(1) topological quantum numbers ...

2011