Publications de 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, Christian Rüegg, Nicola Colonna

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, Christian Rüegg, Gregory Scott Tucker

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

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

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, Gregory Scott Tucker, Christian Rüegg, Nicolas Laflorencie

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

Christian Rüegg, Daniel Biner, Shang Gao

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