Publications de Bruce Normand | EPFL Graph Search

Publications associées (40)

Molecular intercalation in the van der Waals antiferromagnets FePS3 and NiPS3

We have performed electrochemical treatment of the van der Waals antiferromagnetic materials FePS3 and NiPS3 with the ionic liquid EMIM-BF4, achieving significant molecular intercalation. Mass analysis of the intercalated compounds, EMIMx-FePS3 and EMIMx-N ...

Amer Physical Soc2024

Fingerprints of supersymmetric spin and charge dynamics observed by inelastic neutron scattering

Bruce Normand, Andreas Martin Läuchli Herzig

Supersymmetry is an algebraic property of a quantum Hamiltonian that, by giving every boson a fermionic superpartner and vice versa, may underpin physics beyond the Standard Model. Fractional bosonic and fermionic quasiparticles are familiar in condensed m ...

NATURE PORTFOLIO2025

Confined and Deconfined Spinon Excitations in the Rectangular-lattice Quantum Antiferromagnet

Henrik Moodysson Rønnow, Bruce Normand, Ellen Fogh, Noore Elahi Shaik

Fractionalization remains one of the most fascinating manifestations of strong interactions in quantum many-body systems. In quantum magnetism, the existence of spinons-collective magnetic excitations that behave as quasiparticles with fractional quantum n ...

AMER PHYSICAL SOC2025

Quantum Monte Carlo simulations in the trimer basis: First-order transitions and thermal critical points in frustrated trilayer magnets

Frédéric Mila, Bruce Normand

The phase diagrams of highly frustrated quantum spin systems can exhibit first-order quantum phase transitions and thermal critical points even in the absence of any long-ranged magnetic order. However, all unbiased numerical techniques for investigating f ...

SCIPOST FOUNDATION2022

Systematic extraction of crystal electric-field effects and quantum magnetic model parameters in triangular rare-earth magnets

Bruce Normand

A primary goal at the interface of theoretical and experimental quantum magnetism is the investigation of exotic spin states, mostly notably quantum spin liquids (QSLs) that realize phenomena including quasiparticle fractionalization, long-ranged entanglem ...

2021

Spin dynamics in the square-lattice cupola system Ba(TiO)Cu-4(PO4)(4)

Henrik Moodysson Rønnow, Peter Babkevich, Bruce Normand, Luc Testa, Virgile Yves Favre

We report high-resolution single-crystal inelastic neutron scattering measurements on the spin-1/2 antiferromagnet Ba(TiO)Cu-4(PO4)(4). This material is formed from layers of four-site "cupola" structures, oriented alternately upwards and downwards, which ...

AMER PHYSICAL SOC2022

Complete field-induced spectral response of the spin-1/2 triangular-lattice antiferromagnet CsYbSe2

Bruce Normand, Andreas Martin Läuchli Herzig

Fifty years after Anderson's resonating valence-bond proposal, the spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) remains the ultimate platform to explore highly entangled quantum spin states in proximity to magnetic order. Yb-based delafos ...

Nature Portfolio2023

Multi-triplet bound states and finite-temperature dynamics in highly frustrated quantum spin ladders

Frédéric Mila, Bruce Normand

Low-dimensional quantum magnets at finite temperatures present a complex interplay of quantum and thermal fluctuation effects in a restricted phase space. While some information about dynamical response functions is available from theoretical studies of th ...

2016

Field-controlled multicritical behavior and emergent universality in fully frustrated quantum magnets

Bruce Normand

Phase transitions in condensed matter are a source of exotic emergent properties. We study the fully frustrated bilayer Heisenberg antiferromagnet to demonstrate that an applied magnetic field creates a previously unknown emergent criticality. The quantum ...

Nature Portfolio2024

Superconductivity in nickelate and cuprate superconductors with strong bilayer coupling

Bruce Normand

The discovery of superconductivity at 80 K under high pressure in La3Ni2O7 3 Ni 2 O 7 presents the groundbreaking confirmation that high-Tc T c superconductivity is a property of strongly correlated materials beyond cuprates. We use density functional theo ...

AMER PHYSICAL SOC2024

Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4

Henrik Moodysson Rønnow, Joël Mesot, Bruce Normand, Christian Rüegg, Pierre Bouillot, Daniel Biner

Neutron diffraction is used to investigate the field-induced, antiferromagnetically ordered state in the two-leg spin-ladder material (Hpip)(2)CuBr4. This "classical" phase, a consequence of weak interladder coupling, is nevertheless highly unconventional: ...

2009

Ultrafast frustration breaking and magnetophononic driving of singlet excitations in a quantum magnet

Bruce Normand, Nicola Colonna, Christian Rüegg

Ideal magnetic frustration forms the basis for the emergence of exotic quantum spin states that are entirely nonmagnetic. Such singlet spin states are the defining feature of the Shastry-Sutherland model, and of its faithful materials realization in the qu ...

2023

Triplons, magnons, and spinons in a single quantum spin system: SeCuO3

Helmuth Berger, Henrik Moodysson Rønnow, Ivica Zivkovic, Bruce Normand, Luc Testa

Quantum magnets display a wide variety of collective excitations, including spin waves (magnons), coherent singlet-triplet excitations (triplons), and pairs of fractional spins (spinons). These modes differ radically in nature and properties, and in all co ...

AMER PHYSICAL SOC2021

Randomness and frustration in a S = (1/)(2) square-lattice Heisenberg antiferromagnet

Henrik Moodysson Rønnow, Peter Babkevich, Bruce Normand, Ellen Fogh

We explore the interplay between randomness and magnetic frustration in the series of S = 12 Heisenberg square-lattice compounds Sr2CuTe1???xWxO6. Substituting W for Te alters the magnetic interactions dramatically, from strongly nearest-neighbor to next-n ...

2022

Thermodynamic properties of the Shastry-Sutherland model from quantum Monte Carlo simulations

Frédéric Mila, Bruce Normand

We investigate the minus-sign problem that afflicts quantum Monte Carlo (QMC) simulations of frustrated quantum spin systems, focusing on spin S = 1/2, two spatial dimensions, and the extended Shastry-Sutherland model. We show that formulating the Hamilton ...

2018

Multinode quantum spin liquids in extended Kitaev honeycomb models

Bruce Normand

Variational Monte Carlo (VMC) studies of extended Kitaev honeycomb models reveal a series of multinode quantum spin liquids (QSLs). They have an emergent Z2 gauge structure, a discrete number of symmetry-protected Majorana cones, and form Abelian or non-Ab ...

Springer2024

Investigating field-induced magnetic order in Han purple by neutron scattering up to 25.9 T

Frédéric Mila, Philippe Heller, Bruce Normand

BaCuSi2O6 is a quasi-two-dimensional (2D) quantum antiferromagnet containing three different types of stacked, square-lattice bilayer hosting spin-1/2 dimers. Although this compound has been studied extensively over the last two decades, the critical appli ...

2022

Revealing three-dimensional quantum criticality by Sr substitution in Han purple

Frédéric Mila, Bruce Normand, Gregory Scott Tucker, Christian Rüegg

Classical and quantum phase transitions (QPTs), with their accompanying concepts of criticality and universality, are a cornerstone of statistical thermodynamics. An excellent example of a controlled QPT is the field-induced ordering of a gapped quantum ma ...

2021

Thermodynamic properties of highly frustrated quantum spin ladders: Influence of many-particle bound states

Frédéric Mila, Bruce Normand

Quantum antiferromagnets have proven to be some of the cleanest realizations available for theoretical, numerical, and experimental studies of quantum fluctuation effects. At finite temperatures, however, the additional effects of thermal fluctuations in t ...

2016

Field-induced bound-state condensation and spin-nematic phase in SrCu2(BO3)2 revealed by neutron scattering up to 25.9 T

Henrik Moodysson Rønnow, Frédéric Mila, Bruce Normand, Jian Rui Soh, Ellen Fogh, Mithilesh Nayak, Alexandra Angeline Turrini

In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the Bose-Einstein condensation (BEC) of magnon excitations. In the strongly frustrated system SrCu2(BO3)(2), no clear magnon BEC could be observed, point ...

Nature Portfolio2024