Publications by Ellen Fogh | EPFL Graph Search

Demagnetization factors and field of hemispherical objects

Demagnetization factors play an important role in micromagnetics modeling but exact solutions only exist for a limited number of particle shapes. Here we use a Fourier space based approach coupled to the concept of magnetic charges to derive analytically t ...

2025

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

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

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

Bullet pressure-cell design for neutron scattering experiments with horizontal magnetic fields and dilution temperatures

Richard Gaal, Henrik Moodysson Rønnow, Luc Testa, Gaétan Charles Antoine Giriat, Ellen Fogh, Jana Pásztorová

The simultaneous application of high magnetic fields and high pressures for controlling magnetic ground states is important for testing our understanding of many-body quantum theory. However, the implementation for neutron scattering experiments presents a ...

2025

Cooper Pairs of Bosons in a Quantum Magnet Revealed by Neutron Spectroscopy Under Very High Magnetic Fields

Ellen Fogh

2024

Magnon interactions in a moderately correlated Mott insulator

Henrik Moodysson Rønnow, Noore Elahi Shaik, Ellen Fogh

Quantum fluctuations in low-dimensional systems and near quantum phase transitions have significant influences on material properties. Yet, it is difficult to experimentally gauge the strength and importance of quantum fluctuations. Here we provide a reson ...

Nature Research2024

Magnetic structure and magnetoelectric properties of the spin-flop phase in LiFePO4

Sofie Janas, Ellen Fogh, Paola Caterina Forino

We investigate the magnetic structure and magnetoelectric(ME) effect in the high -field phase of the antiferromagnet LiFePO 4 above the critical field of 31 T. A neutron diffraction study in pulsed magnetic fields reveals the propagation vector to be q = 0 ...

Amer Physical Soc2024

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

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

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

Spin Waves and Three Dimensionality in the High-Pressure Antiferromagnetic Phase of SrCu2 (BO3)2

Frédéric Mila, Bruce Normand, Henrik Moodysson Rønnow, Gaétan Charles Antoine Giriat, Ellen Fogh, Jian Rui Soh

Quantum magnetic materials can provide explicit realizations of paradigm models in quantum many-body physics. In this context, SrCu2(BO3)2 is a faithful realization of the Shastry-Sutherland model for ideally frustrated spin dimers, even displaying several ...

2024

Electrical and Magnetic Properties of FeGa3 with Antisite Disorder

Henrik Moodysson Rønnow, Ivica Zivkovic, Ellen Fogh

We investigated the electronic and magnetic ground states of the cage compound FeGa3 under the presence of Fe antisite disorder (namely as Fe0.258Ga0.742) by x-ray diffraction (XRD), Mössbauer spectroscopy (MS), magnetization and electrical resistivity. Ou ...

2023

The magnetoelectric effect in LiFePO4 - Revisited (vol 648, 414380, 2022)

Henrik Moodysson Rønnow, Alexandre Pages, Ellen Fogh

ELSEVIER2023

Tuning magnetoelectricity in a mixed-anisotropy antiferromagnet

Henrik Moodysson Rønnow, Ellen Fogh, Jian Rui Soh

Control of magnetization and electric polarization is attractive in relation to tailoring materials for data storage and devices such as sensors or antennae. In magnetoelectric materials, these degrees of freedom are closely coupled, allowing polarization ...

Nature Portfolio2023

Structure, Spin Correlations, and Magnetism of the S=1/2 Square-Lattice Antiferromagnet Sr2CuTe1-xWxO6 (0 ≤ x ≤ 1)

Henrik Moodysson Rønnow, Peter Babkevich, Sami Juhani Vasala, Ellen Fogh

Quantum spin liquids are highly entangled magnetic states with exotic properties. The S = 1/2 square-lattice Heisenberg model is one of the foundational models in frustrated magnetism with a predicted, but never observed, quantum spin liquid state. Isostru ...

Amer Chemical Soc2023

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

Bruce Normand, Henrik Moodysson Rønnow, Peter Babkevich, 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

A quantum magnetic analogue to the critical point of water

Mohamed Zayed, Ludger Weber, Frédéric Mila, Bruce Normand, Henrik Moodysson Rønnow, Julio Antonio Larrea Jiménez, Kazimierz Conder, Ellen Fogh, Christian Rüegg

At the liquid-gas phase transition in water, the density has a discontinuity at atmospheric pressure; however, the line of these first-order transitions defined by increasing the applied pressure terminates at the critical point(1), a concept ubiquitous in ...

2021

Magnetic structures and quadratic magnetoelectric effect in LiNiPO4 beyond 30 T

Ellen Fogh

Neutron diffraction with static and pulsed magnetic fields is used to directly probe the magnetic structures in LiNiPO4 up to 25 T and 42 T, respectively. By combining these results with magnetometry and electric polarization measurements under pulsed fiel ...

AMER PHYSICAL SOC2020