Concept

Séparation spin-charge

Publications associées (26)

Nonlinear optical diode effect in a magnetic Weyl semimetal

Diode effects are of great interest for both fundamental physics and modern technologies. Electrical diode effects (nonreciprocal transport) have been observed in Weyl systems. Optical diode effects arising from the Weyl fermions have been theoretically co ...

Nature Portfolio2024

Exciton migration in two-dimensional materials

Giovanni Consalvo Cistaro

Excitons play an essential role in the optical response of two-dimensional materials. These are bound states showing up in the band gaps of many-body systems and are conceived as quasiparticles formed by an electron and a hole. By performing real-time simu ...

Nature Portfolio2024

Numerical investigation of bound states in quantum magnets

Mithilesh Nayak

Bound-states of particles are an interesting problem in quantum mechanics dating back to 1931 Bethe's solution of spin-1/2 Heisenberg chain. These exotic composite states are realized in quantum magnets and are detectable in inelastic neutron scattering (I ...

EPFL2023

Static and dynamic properties of non-collinear quantum antiferromagnets explored by neutron scattering

Luc Testa

This thesis is devoted to the investigation of static and dynamic properties of two different sets of quantum magnets with neutron scattering techniques and the help of linear spin wave theory. Both systems are copper-based with spin-1/2, which makes them ...

EPFL2021

Topological magnon insulators in two-dimensional van der Waals ferromagnets CrSiTe3 and CrGeTe3: Toward intrinsic gap-tunability

Flaviano José Dos Santos

The bosonic analogs of topological insulators have been proposed in numerous theoretical works, but their experimental realization is still very rare, especially for spin systems. Recently, two-dimensional (2D) honeycomb van der Waals ferromagnets have eme ...

2021

Spinon confinement and deconfinement in spin-1 chains

Frédéric Mila, Natalia Chepiga

Motivated by the rich phase diagrams recently unveiled in frustrated spin-1 chains with competing next-nearest-neighbor and four-spin interactions, we investigate the nature of the elementary excitations of spin-1 chains in the vicinity of phase transition ...

2020

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

Coexisting spinons and magnons in the frustrated zigzag spin-1/2 chain compound beta-TeVO4

Helmuth Berger

We investigate magnetic excitations in the frustrated zigzag spin-1/2 chain compound beta-TeVO4 by inelastic neutron scattering. In the magnetically ordered ground state, the excitation spectrum exhibits coexisting magnon dispersion, characteristic of long ...

AMER PHYSICAL SOC2018

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

Luttinger liquid behavior in the alternating spin-chain system copper nitrate

Felix Groitl

We determine the phase diagram of copper nitrate Cu(NO3)(2)center dot 2.5D(2)O in the context of quantum phase transitions and novel states of matter. We establish this compound as an ideal candidate to study quasi-1D Luttinger liquids, 3D Bose-Einstein-Co ...

American Physical Society2015

Fractional excitations in the square-lattice quantum antiferromagnet

Henrik Moodysson Rønnow, Dmitri Ivanov, Bastien Dalla Piazza, Martin Mourigal

Quantum magnets have occupied the fertile ground between many-body theory and low-temperature experiments on real materials since the early days of quantum mechanics. However, our understanding of even deceptively simple systems of interacting spin-1/2 par ...

Nature Publishing Group2015

Direct measurement of the bulk spin structure of noncentrosymmetric BiTeCl

Jan Hugo Dil, Stefan Peter Muff

A strong spin-orbit interaction leads to a Rashba-type splitting of the bulk bands of BiTeCl, which results in toroidal Fermi surfaces with distinct spin structures depending on the chemical potential. Here, we present spin-and angle-resolved photoelectron ...

American Physical Society2015

Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy

Majed Chergui, Thomas James Penfold, Jochen Rittmann, Andrea Lübcke

Picosecond X-ray absorption spectroscopy (XAS) is used to investigate the electronic and structural dynamics initiated by plasmon excitation of 1.8 nm diameter Au nanoparticles (NPs) functionalised with 1-hexanethiol. We show that 100 ps after photoexcitat ...

Royal Society of Chemistry2014

Interplay of Dirac fermions and heavy quasiparticles in solids

Thorsten Schmitt

Many-body interactions in crystalline solids can be conveniently described in terms of quasiparticles with strongly renormalized masses as compared with those of non-interacting particles. Examples of extreme mass renormalization are on the one hand graphe ...

Nature Publishing Group2013

Experimental evidence for Luttinger liquid behavior in sufficiently long GaAs V-groove quantum wires

Elyahou Kapon, Alok Rudra, Benjamin Dwir

We have measured the temperature dependence of the conductance of long V-groove quantum wires fabricated using GaAs/AlGaAs heterostructures, in a wide temperature range (200 mK < T < 4.2 K). We find that for our quantum wires the Fermi velocity can be as l ...

2012

Spin-orbital separation in the quasi-one-dimensional Mott insulator Sr2CuO3

Henrik Moodysson Rønnow, Thorsten Schmitt, Martin Mourigal

When viewed as an elementary particle, the electron has spin and charge. When binding to the atomic nucleus, it also acquires an angular momentum quantum number corresponding to the quantized atomic orbital it occupies. Even if electrons in solids form ban ...

2012

Spin-Orbital Quantum Liquid on the Honeycomb Lattice

Frédéric Mila, 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

Femtosecond UV Studies of the Electronic Relaxation Processes in Cytochrome c

Majed Chergui, Andrea Cannizzo, Olivier Christian Bräm, Cristina Consani

We report on an experimental study with UV and visible ultrafast time-gated emission and transient absorption of the early photodynamics of horse heart Cytochrome c in both ferric and ferrous redox states. A clear separation in time and energy of tryptopha ...

2011

On Zero-Dimensional Exciton-Polaritons

Roland Cerna

Microcavity exciton-polaritons are half-matter half-light quasiparticles with outstanding properties. This offers a great way to access and control fundamental excitations in a solid by simple optical means. Therefore, apart from their importance in fundam ...

EPFL2011

Phase diagram and continuous pair-unbinding transition of the bilinear-biquadratic S=1 Heisenberg chain in a magnetic field

Frédéric Mila

We investigate the properties of the Heisenberg S = 1 chain with bilinear and biquadratic interactions in a magnetic field using the density-matrix renormalization-group, Bethe ansatz, and field-theoretical considerations. In a large region of the paramete ...

2011