Publications by Christian Rüegg

Structural and magnetic properties of β-Li2IrO3 after grazing-angle focused ion beam thinning

Manipulating the size and orientation of quantum materials is often used to tune emergent phenomena, but precise control of these parameters is also necessary from an experimental point of view. Various synthesis techniques already exist, such as epitaxial ...

2025

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

Thermal Evolution of Dirac Magnons in the Honeycomb Ferromagnet CrBr3

Andreas Martin Läuchli Herzig, Bruce Normand, Christian Rüegg

CrBr3 is an excellent realization of the two-dimensional honeycomb ferromagnet, which offers a bosonic equivalent of graphene with Dirac magnons and topological character. We perform inelastic neutron scattering measurements using state-of-the-art instrume ...

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

Magnetic order in the quasi-one-dimensional Ising system RbCoCl3

Bruce Normand, Christian Rüegg

In RbCoCl3, the magnetic Co2+ ions form weakly coupled Ising chains arranged on a triangular lattice. We have investigated the structure and magnetism in RbCoCl3 by high-resolution x-ray diffraction and neutron scattering measurements on powder and single- ...

2021

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

Multiple Magnetic Bilayers and Unconventional Criticality without Frustration in BaCuSi2O6

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

The dimerized quantum magnet BaCuSi2O6 was proposed as an example of "dimensional reduction" arising near the magnetic-field-induced quantum critical point (QCP) due to perfect geometrical frustration of its interbilayer interactions. We demonstrate by hig ...

2020

Crystal electric field excitations in the quantum spin liquid candidate NaErS2

Shang Gao, Daniel Biner, Christian Rüegg

The delafossite family of compounds with a triangular lattice of rare earth ions has been recently proposed as a candidate host for quantum spin liquid (QSL) states. To realize QSLs, the crystal electric field (CEF) ground state of the rare earth ions shou ...

AMER PHYSICAL SOC2020

Narrow-band and tunable intense terahertz pulses for mode-selective coherent phonon excitation

Christian Rüegg

We generate frequency-tunable narrow-band intense fields in the terahertz (THz) range by optical rectification of a temporally modulated near-infrared laser pumping a nonlinear organic crystal. Carrier-frequency tunability between 0.5 and 6.5THz is achieve ...

2020

Thermal Control of Spin Excitations in the Coupled Ising-Chain Material RbCoCl3

Bruce Normand, Christian Rüegg

We have used neutron spectroscopy to investigate the spin dynamics of the quantum (S = 1/2) antiferromagnetic Ising chains in RbCoCl3. The structure and magnetic interactions in this material conspire to produce two magnetic phase transitions at low temper ...

2020

Tomonaga-Luttinger Liquid Spin Dynamics in the Quasi-One-Dimensional Ising-Like Antiferromagnet BaCo2V2O8

Thierry Giamarchi, Martin Mansson, Jonathan White, Gregory Scott Tucker, Christian Rüegg

Combining inelastic neutron scattering and numerical simulations, we study the quasi-one-dimensional Ising anisotropic quantum antiferromagnet BaCo2V2O8 in a longitudinal magnetic field. This material shows a quantum phase transition from a Neel ordered ph ...

AMER PHYSICAL SOC2019

Bound States and Field-Polarized Haldane Modes in a Quantum Spin Ladder

Bruce Normand, Pierre Bouillot, Daniel Biner, Christian Rüegg

The challenge of one-dimensional systems is to understand their physics beyond the level of known elementary excitations. By high-resolution neutron spectroscopy in a quantum spin-ladder material, we probe the leading multiparticle excitation by characteri ...

Amer Physical Soc2017

CAMEA—A novel multiplexing analyzer for neutron spectroscopy

Henrik Moodysson Rønnow, Felix Groitl, Christian Rüegg

The analyzerdetector system continuous angle multiple energy analysis will be installed on the cold-neutron triple-axis spectrometer RITA-2 at SINQ, PSI. CAMEA is optimized for efficiency in the horizontal scattering plane enabling rapid and detailed mappi ...

American Institute of Physics2016

Electromagnon dispersion probed by inelastic X-ray scattering in LiCrO2

Henrik Moodysson Rønnow, Sándor Tóth, Christian Rüegg

Inelastic X-ray scattering with meV energy resolution (IXS) is an ideal tool to measure collective excitations in solids and liquids. In non-resonant scattering condition, the cross-section is strongly dominated by lattice vibrations (phonons). However, it ...

Nature Research2016

Field-Induced Quantum Soliton Lattice in a Frustrated Two-Leg Spin-1/2 Ladder

Henrik Moodysson Rønnow, Joël Mesot, Shuang Wang, Kazimierz Conder, Siyuan Wang, Christian Rüegg

Based on high-field 31P nuclear magnetic resonance experiments and accompanying numerical calculations, it is argued that in the frustrated S=1/2 ladder compound BiCu2PO6 a field-induced soliton lattice develops above a critical field of μ0Hc1=20.96(7) T. ...

American Physical Society2013

Robustness of Basal-Plane Antiferromagnetic Order and the Jeff=1/2 State in Single-Layer Iridate Spin-Orbit Mott Insulators

Henrik Moodysson Rønnow, Christian Rüegg

The magnetic structure and electronic ground state of the layered perovskite Ba2IrO4 have been investigated using x-ray resonant magnetic scattering. Our results are compared with those for Sr2IrO4, for which we provide supplementary data on its magnetic s ...

American Physical Society2013

Anisotropic Cascade of Field-Induced Phase Transitions in the Frustrated Spin-Ladder System BiCu_{2}PO_{6}

Krunoslav Prsa, Henrik Moodysson Rønnow, Shuang Wang, Christian Rüegg

BiCu2PO6 is a frustrated two-leg spin-ladder compound with a spin gap that can be closed with a magnetic field of approximately 20 T. This quantum phase transition and its related phase diagram as a function of magnetic field and temperature (H, T) are inv ...

Amer Physical Soc2012

68Ga-NODAGA-RGDyK for αvβ3 integrin PET imaging. Preclinical investigation and dosimetry

Serge Baechler, David Viertl, Carole Poitry-Yamate, Christian Rüegg

To visualize neovasculature and/or tumour integrin αvβ3 we selected the binding moiety Arg-Gly-Asp-D-Tyr-Lys (RGDyK) coupled to NODAGA for labeling with 68Ga. ...

Schattauer2011

Crystal growth and characterization of the dilutable frustrated spin-ladder compound Bi(Cu1-xZnx)(2)PO6

Henrik Moodysson Rønnow, Neda Nikseresht Ghanepour, Shuang Wang, Kazimierz Conder, Siyuan Wang, Christian Rüegg

High quality centimeter size single crystals of Bi(Cu1-xZnx)(2)PO6 (x=0% 1% 5%) have been successfully grown by the Travelling Solvent Floating Zone (TSFZ) technique The crystals were grown with a rate of 1 mm/h in a gas mixture of 20% O-2 in Ar Characteri ...

Elsevier2010

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

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

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