Publications related to Landau theory

Nonperturbative aspects of scattering amplitudes

In this thesis we study how physical principles imposed on the S-matrix, such as Lorentz invariance, unitarity, crossing symmetry and analyticity constrain quantum field theories at the nonperturbative level. We start with a pedagogical introduction to the ...

EPFL2023

Hamiltonian truncation in Anti-de Sitter spacetime

Kamran Salehi Vaziri, João Miguel Augusto Penedones Fernandes, Marco Meineri, Matthijs Jan Hogervorst

Quantum Field Theories (QFTs) in Anti-de Sitter (AdS) spacetime are often strongly coupled when the radius of AdS is large, and few methods are available to study them. In this work, we develop a Hamiltonian truncation method to compute the energy spectrum ...

Springer Nature2021

On the fractal structure of soil moisture fields

Andrea Rinaldo

We study the spatial structure of soil moisture fields within savanna ecosystems, whose persistence is vital because it is the driver of the entire ecological structure and function. These include changes in the physical and biogeochemical conditions of th ...

ELSEVIER SCI LTD2021

Infinitesimal asphericity changes the universality of the jamming transition

Matthieu Wyart, Carolina Brito Carvalho dos Santos

The jamming transition of non-spherical particles is fundamentally different from the spherical case. Non-spherical particles are hypostatic at their jamming points, while isostaticity is ensured in the case of the jamming of spherical particles. This stru ...

IOP PUBLISHING LTD2020

Quantum phase transitions beyond Landau-Ginzburg theory in one-dimensional space revisited

Christopher Marc Mudry

The phase diagram of the quantum spin-1/2 antiferromagnetic J(1)-J(2) XXZ chain was obtained by Haldane using bosonization techniques [Haldane, Phys. Rev. B 25, 4925 (1982); 26, 5257 (1982)]. It supports three distinct phases for 0

2019

Studies in strongly coupled quantum field theories and renormalization group flows

Bernardo Zan

This thesis presents studies in strongly coupled Renormalization Group (RG) flows. In the first part, we analyze the subject of non-local Conformal Field Theories (CFTs), arising as continuous phase transitions of statistical models with long-range interac ...

EPFL2019

Structure and superconductivity in the binary Re1-xMox alloys

Joël Mesot

The binary Re1-xMox alloys, known to cover the full range of solid solutions, were successfully synthesized and their crystal structures and physical properties investigated via powder x-ray diffraction, electrical resistivity, magnetic susceptibility, and ...

AMER PHYSICAL SOC2019

Universality of jamming of nonspherical particles

Matthieu Wyart, Carolina Brito Carvalho dos Santos

Amorphous packings of nonspherical particles such as ellipsoids and spherocylinders are known to be hypostatic: The number of mechanical contacts between particles is smaller than the number of degrees of freedom, thus violating Maxwell's mechanical stabil ...

National Academy of Sciences2018

Thermal Critical Points and Quantum Critical End Point in the Frustrated Bilayer Heisenberg Antiferromagnet

Frédéric Mila, Bruce Normand

We consider the finite-temperature phase diagram of the S = 1/2 frustrated Heisenberg bilayer. Although this two-dimensional system may show magnetic order only at zero temperature, we demonstrate the presence of a line of finite-temperature critical point ...

2018

Dimerization and exotic criticality in spin-S chains

Natalia Chepiga

In this thesis we have studied the emergence of spontaneously dimerized phases in frustrated spin-S chains, with emphasis on the nature of the critical lines between the dimerized and non-dimerized phases. The main numerical method used in this thesis is t ...

EPFL2017

Dimensional Reduction in Quantum Dipolar Antiferromagnets

Henrik Moodysson Rønnow, Martin Mansson, Peter Babkevich, Ivan Kovacevic

We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF4. For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent -0 ...

2016

Comment on “Frustration and multicriticality in the antiferromagnetic spin-1 chain”

Frédéric Mila, Natalia Chepiga

The phase diagram of the spin-1 chain with bilinear-biquadratic and next-nearest-neighbor interactions, recently investigated by Pixley, Shashi, and Nevidomskyy [Phys. Rev. B 90, 214426 (2014)], has been revisited in the light of results we have recently o ...

2016

Phase diagram of diluted Ising ferromagnet LiHoxY1-xF4

Henrik Moodysson Rønnow, Peter Babkevich, Bastien Dalla Piazza, Julian Piatek, Neda Nikseresht Ghanepour, Conradin Kraemer, Ivan Kovacevic

We present a systematic study of the phase diagram of LiHoxY1-xF4 (0.25

Amer Physical Soc2016

Upper critical field, pressure-dependent superconductivity and electronic anisotropy of Sm4Fe2As2Te1-xO4-yFy

László Forró, Andrea Pisoni, Richard Gaal, Bálint Náfrádi, Janusz Andrzej Karpinski, Sergiy Katrych, Péter Szirmai

We present a detailed study of the electrical transport properties of a recently discovered iron-based superconductor: Sm4Fe2As2Te0.72O2.8F1.2. We followed the temperature dependence of the upper critical field by resistivity measurement of single crystals ...

Iop Publishing Ltd2016

Single crystals of superconducting SmFeAsOHx: Structure and properties

László Forró, Andrea Pisoni, Alla Arakcheeva, Richard Gaal, Janusz Andrzej Karpinski, Sergiy Katrych, Ping Huang, Péter Krisztián Matus

We report the synthesis, structure, and superconducting properties of single crystals of SmFeAsOHx. The crystals were grown at high pressure and high temperature using a cubic anvil technique. H-1-NMR studies confirm the presence of H atoms in the samples. ...

Amer Physical Soc2016

Importance of XY anisotropy in Sr2IrO4 revealed by magnetic critical scattering experiments

Henrik Moodysson Rønnow

The magnetic critical scattering in Sr2IrO4 has been characterized using x-ray resonant magnetic scattering (XRMS) both below and above the three-dimensional antiferromagnetic ordering temperature T-N. The order parameter critical exponent below TN is foun ...

2015

Scaling in the quantum Hall regime of graphene Corbino devices

Klaus Kern, Marko Burghard, Eva Carmen Peters

The scaling behavior of graphene devices in Corbino geometry was investigated through temperature dependent conductivity measurements under magnetic field. Evaluation of the Landau level width as a function of temperature yielded a relatively low temperatu ...

Amer Inst Physics2014

Nonlinear Midinfrared Photothermal Spectroscopy Using Zharov Splitting and Quantum Cascade Lasers

Hatice Altug, Shyamsunder Erramilli, Mi Kyung Hong

We report on the Mid-infrared nonlinear photothermal spectrum of the neat liquid crystal 4-octyl-4'-cyanobiphenyl (8CB) using a tunable Quantum Cascade Laser (QCL). The nonequilibrium steady state characterized by the nonlinear photothermal infrared respon ...

2014

Sampling 2-D Signals on a Union of Lattices that Intersect on a Lattice

Jayakrishnan Unnikrishnan

This paper presents new sufficient conditions under which a field (or image) can be perfectly reconstructed from its samples on a union of two lattices that share a common coarse lattice. In particular, if samples taken on the first lattice can be used to ...

Ieee2014

Study of the twinned dendrite tip shape I : Phase-field modeling

Michel Rappaz, Jean-Luc Desbiolles, Mario Alberto Salgado Ordorica

The growth kinetics advantage of twinned aluminum dendrites over regular ones is still an unsolved problem of solidification. Although it is linked to the tip geometry, the influence of a coherent (1 1 1) twin plane on a < 1 1 0 > twinned dendrite tip is u ...

Elsevier2011