Publications de Gregory Scott Tucker

Topological magnon band structure of emergent Landau levels in a skyrmion lattice

The motion of a spin excitation across topologically nontrivial magnetic order exhibits a deflection that is analogous to the effect of the Lorentz force on an electrically charged particle in an orbital magnetic field. We used polarized inelastic neutron ...

American Association for the Advancement of Science2022

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

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

Multiphase magnetism in Yb2Ti2O7

Gregory Scott Tucker

We use neutron scattering to show that ferromagnetism and antiferromagnetism coexist in the low T state of the pyrochlore quantum magnet Yb2Ti2O7. While magnetic Bragg peaks evidence long-range static ferromagnetic order, inelastic scattering shows that sh ...

National Academy of Sciences2020

Energy domain versus time domain precursor fluctuations above the Verwey transition in magnetite

Henrik Moodysson Rønnow, Fabrizio Carbone, Simone Borroni, Gregory Scott Tucker

We study the dynamics and interactions of the critical fluctuations of the Verwey transition in magnetite (Fe3O4) in the pretransition region by means of inelastic neutron scattering experiments on a natural single crystal. We find that a Delta(5) mode int ...

AMER PHYSICAL SOC2020

Metastable and localized Ising magnetism in alpha-CoV2O6 magnetization plateaus

Gregory Scott Tucker

alpha-CoV2O6 consists of j(eff) = 1/2 Ising to investigate the magnetic periodicity in the vicinity of these plateaus. We find these steps to be characterized by metastable and spatially short-range (xi similar to 10 angstrom) magnetic correlations with an ...

AMER PHYSICAL SOC2020

Ferrimagnetic 120 degrees magnetic structure in Cu2OSO4

Helmuth Berger, Arnaud Magrez, Henrik Moodysson Rønnow, Ivica Zivkovic, Virgile Yves Favre, Lin Yang, Romain Sibille, Gregory Scott Tucker, Nicola Casati

We report magnetic properties of a 3d(9) (Cu2+) magnetic insulator Cu2OSO4 measured on both powder and single crystal. The magnetic atoms of this compound form layers whose geometry can be described either as a system of chains coupled through dimers or as ...

AMER PHYSICAL SOC2020

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

Field dependence of nonreciprocal magnons in chiral MnSi

Gregory Scott Tucker

2018

Non-reciprocal magnons in non-centrosymmetric MnSi

Thomas Alois Weber, Gregory Scott Tucker

Using two cold-neutron triple-axis spectrometers we have succeeded in fully mapping out the field-dependent evolution of the non-reciprocal magnon dispersion relations in all magnetic phases of MnSi. The non-reciprocal nature of the dispersion manifests it ...

2018

Mapping the lattice dynamical anomaly of the order parameters across the Verwey transition in magnetite

Henrik Moodysson Rønnow, Fabrizio Carbone, Andrea Pisoni, Francesco Pennacchio, Simone Borroni, Gregory Scott Tucker

We present inelastic neutron scattering data across the Verwey transition in magnetite, obtained for a single crystal via a detwinning method. We provide direct evidence of the influence of the charge order on the transverse-acoustic phonons, associated wi ...

2017

Magnetic quadrupolar order in the chiral square cupola compound BaTiOCu4(PO4)4

Henrik Moodysson Rønnow, Luc Testa, Peter Babkevich, Gregory Scott Tucker

We report neutron diffraction studies of the magnetic structure in BaTiOCu4(PO4)4 , which is a newly discovered magneticinsulator crystallizing in a tetragonal chiral crystal structure with P4212 space group [1]. The crystal structure ischaracterized by an ...

2017

Magnetic structure of Ba(TiO)Cu4(PO4)4 probed using spherical neutron polarimetry

Henrik Moodysson Rønnow, Luc Testa, Peter Babkevich, Gregory Scott Tucker

The antiferromagnetic compound Ba(TiO)Cu4(PO4)4 contains square cupola of corner-sharing CuO4 plaquettes, which were proposed to form effective quadrupolar order. To identify the magnetic structure, we have performed spherical neutron polarimetry measureme ...

2017

Spiral spin-liquid and the emergence of a vortex-like state in MnSc2S4

Jonathan White, Shang Gao, Romain Sibille, Gregory Scott Tucker

Spirals and helices are common motifs of long-range order in magnetic solids, and they may also be organized into more complex emergent structures such as magnetic skyrmions and vortices. A new type of spiral state, the spiral spin-liquid, in which spins f ...

Nature Publishing Group2017

Spin excitations in the skyrmion host Cu2OSeO3

Arnaud Magrez, Henrik Moodysson Rønnow, Ivica Zivkovic, Jonathan White, Peter Babkevich, Ping Huang, Felix Groitl, Gregory Scott Tucker

We have used inelastic neutron scattering to measure the magnetic excitation spectrum along the high-symmetry directions of the first Brillouin zone of the magnetic skyrmion hosting compound Cu2OSeO3. The majority of our scattering data are consistent with ...

Amer Physical Soc2016

Magnetodielectric detection of magnetic quadrupole order in Ba(TiO)Cu4(PO4)4 with Cu4O12 square cupolas

Henrik Moodysson Rønnow, Peter Babkevich, Julia Martius, Gregory Scott Tucker

In vortex-like spin arrangements, multiple spins can combine into emergent multipole moments. Such multipole moments have broken space-inversion and time-reversal symmetries, and can therefore exhibit linear magnetoelectric (ME) activity. Three types of su ...

Nature Research2016