Publications de Jonathan White

Direct observation of exchange anisotropy in the helimagnetic insulator Cu2OSeO3

Arnaud Magrez, Jonathan White, Chen Luo, Priya Ranjan Baral

The helical magnetic structures of cubic chiral systems are well explained by the competition among Heisen-berg exchange, Dzyaloshinskii-Moriya interaction, cubic anisotropy, and anisotropic exchange interaction (AEI). Recently, the role of the latter has ...

AMER PHYSICAL SOC2023

Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound

Jonathan White, Le Yu

Magnetic skyrmions are topologically stable swirling spin textures with particle-like character, and have been intensively studied as a candidate of high-density information bit. While magnetic skyrmions were originally discovered in noncentrosymmetric sys ...

Nature Research2022

Small-angle neutron scattering study of mesoscale magnetic disordering and skyrmion phase suppression in the frustrated chiral magnet Co6.75Zn6.75Mn6.51

Henrik Moodysson Rønnow, Jonathan White

Co-Zn-Mn chiral cubic magnets display versatile magnetic skyrmion phases, including equilibrium phases stable far above and far below room temperature, and the facile creation of robust far-from-equilibrium skyrmion states. In this system, compositional di ...

INT UNION CRYSTALLOGRAPHY2022

Vital role of magnetocrystalline anisotropy in cubic chiral skyrmion hosts

Henrik Moodysson Rønnow, Jonathan White

Magnetic anisotropy is anticipated to govern the formation of exotic spin textures reported recently in cubic chiral magnets, like low-temperature tilted conical and skyrmion lattice (SkL) states and metastable SkLs with various lattice geometry. Motivated ...

NATURE RESEARCH2021

In situ control of the helical and skyrmion phases in Cu2OSeO3 using high-pressure helium gas up to 5 kbar

Arnaud Magrez, Henrik Moodysson Rønnow, Ivica Zivkovic, Jonathan White

We report a small-angle neutron scattering study of the helical and skyrmion lattice order in single-crystal Cu2OSeO3 under quasihydrostatic helium gas pressures up to 5 kbar. By using helium gas as the pressure-transmitting medium (PTM) we ensure pressure ...

AMER PHYSICAL SOC2020

Metastable skyrmion lattices governed by magnetic disorder and anisotropy in beta-Mn-type chiral magnets

Henrik Moodysson Rønnow, Jonathan White

Magnetic skyrmions are vortexlike topological spin textures often observed in structurally chiral magnets with Dzyaloshinskii-Moriya interaction. Among them, Co-Zn-Mn alloys with a beta-Mn-type chiral structure host skyrmions above room temperature. In thi ...

AMER PHYSICAL SOC2020

Direct Observation of the Statics and Dynamics of Emergent Magnetic Monopoles in a Chiral Magnet

Henrik Moodysson Rønnow, Jonathan White

In the three-dimensional (3D) Heisenberg model, topological point defects known as spin hedgehogs behave as emergent magnetic monopoles, i.e., quantized sources and sinks of gauge fields that couple strongly to conduction electrons, and cause unconventiona ...

AMER PHYSICAL SOC2020

Magnetic ground state of the frustrated spin-1/2 chain compound beta-TeVO4 at high magnetic fields

Helmuth Berger, Jonathan White

Frustrated spin-1/2 chains, despite the apparent simplicity, exhibit a remarkably rich phase diagram comprising vector-chiral (VC), spin-density-wave (SDW), and multipolar/spin-nematic phases as a function of the magnetic field. Here we report a study of b ...

2019

Deformation of the moving magnetic skyrmion lattice in MnSi under electric current flow

Henrik Moodysson Rønnow, Ivica Zivkovic, Jonathan White, Zhuo Quan Im

Topological defects are found ubiquitously in various kinds of matter, such as vortices in type-II superconductors, and magnetic skyrmions in chiral ferromagnets. While knowledge on the static behavior of magnetic skyrmions is accumulating steadily, their ...

Springer2019

Correlation between site occupancies and spin-glass transition in skyrmion host Co10-x/2Zn10-x/2Mnx

Henrik Moodysson Rønnow, Jonathan White

Ternary alloys Co-Zn-Mn with beta-Mn-type structure exhibit helimagnetic order and skyrmion lattice states in a low-Mn-concentration region. Recent studies on Co10-x/2Zn10-x/2Mnx (CZM) revealed that the magnetic modulation period and the paramagnetic-to-he ...

AMER PHYSICAL SOC2019

Elementary excitation in the spin-stripe phase in quantum chains

Helmuth Berger, Jonathan White

Elementary excitations in condensed matter capture the complex many-body dynamics of interacting basic entities in a simple quasiparticle picture. In magnetic systems the most established quasiparticles are magnons, collective excitations that reside in or ...

Springer2019

Bulk single-crystal growth of the theoretically predicted magnetic Weyl semimetals RAlGe (R = Pr, Ce)

Jonathan White, Neeraj Kumar

We explore two methods for single-crystal growth of the theoretically proposed magnetic Weyl semimetals RAlGe (R = Pr, Ce), which prove that a floating-zone technique, being both crucible- and flux-free, is crucial to obtain perfectly stoichiometric RAlGe ...

AMER PHYSICAL SOC2019

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

Negative-pressure-induced helimagnetism in ferromagnetic cubic perovskites Sr1-xBaxCoO3

Henrik Moodysson Rønnow, Jonathan White

Helimagnetic materials are identified as promising for novel spintronic applications. Since helical spin order is manifested as a compromise of competing magnetic exchange interactions, its emergence is limited by unique constraints imposed by the crystall ...

2018

Multiple-q noncollinear magnetism in an itinerant hexagonal magnet

Henrik Moodysson Rønnow, Jonathan White

Multiple-q spin order, i.e., a spin texture characterized by a multiple number of coexisting magnetic modulation vectors q, has recently attracted attention as a source of nontrivial magnetic topology and associated emergent phenomena. One typical example ...

AMER ASSOC ADVANCEMENT SCIENCE2018

Direct electric field control of the skyrmion phase in a magnetoelectric insulator

Henrik Moodysson Rønnow, Ivica Zivkovic, Jonathan White

Magnetic skyrmions are topologically protected spin-whirls currently considered as promising for use in ultra-dense memory devices. Towards achieving this goal, exploration of the skyrmion phase response and under external stimuli is urgently required. Her ...

Nature Research2018

Controlling the helicity of magnetic skyrmions in a beta-Mn-type high-temperature chiral magnet

Henrik Moodysson Rønnow, Jonathan White

Magnetic helices and skyrmions in noncentrosymmetric magnets are representative examples of chiral spin textures in solids. Their spin swirling direction, often termed as the magnetic helicity and defined as either left handed or right handed, is uniquely ...

AMER PHYSICAL SOC2018

Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet

Henrik Moodysson Rønnow, Jonathan White

Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with the Dzyaloshinskii-Moriya interaction. Recently, beta-Mn structure-type Co-Zn-Mn alloys were ident ...

AMER ASSOC ADVANCEMENT SCIENCE2018

Electric-Field-Driven Topological Phase Switching and Skyrmion-Lattice Metastability in Magnetoelectric Cu2OSeO3

Ivica Zivkovic, Jonathan White

American Physical Society (APS)2018

Low-Field Bi-Skyrmion Formation in a Noncentrosymmetric Chimney Ladder Ferromagnet

Henrik Moodysson Rønnow, Jonathan White

2018