Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
CMP
Credit: Jack Hobhouse

Paul Goddard

Visiting Lecturer

Sub department

  • Condensed Matter Physics
Paul.Goddard@physics.ox.ac.uk
Telephone: 01865 (2)72318
Clarendon Laboratory, room 252.1
  • About
  • Publications

Magnetic field induced ordering in the spin-12 chiral chain compound [Cu(pym)(H2O)4]SiF6·H2O

Physical Review B American Physical Society (APS) 112:5 (2025) 054414

Authors:

Rebecca Scatena, Alberto Hernández-Melián, Benjamin M Huddart, Sam Curley, Robert C Williams, Pascal Manuel, Stephen J Blundell, Zurab Guguchia, Zachary E Manson, Jamie L Manson, G Timothy Noe, John Singleton, Tom Lancaster, Paul A Goddard, Roger D Johnson

Abstract:

We present single-crystal neutron diffraction, powder muon spin rotation, and pulsed-field magnetometry measurements on the Heisenberg quantum chiral chain [ Cu ( pym ) ( H 2 O ) 4 ] SiF 6 · H 2 O (pym = pyrimidine), which displays a fourfold-periodic rotation of the local environment around the Cu() S = 1 / 2 ions from site to site along the chain. Previous measurements on this material have shown the absence of magnetic order down to surprisingly low temperatures ≥ 20  mK, as well as the presence of an energy gap for magnetic excitations that grows linearly with magnetic field. Here we find evidence at dilution refrigerator temperatures for a field-induced transition to long-range magnetic order above an applied magnetic field of 3 T. From the polarization of magnetic moments observed with magnetic fields applied in the [ − 1 , 2 , 0 ] direction, we can identify the static magnetic structure that best accounts for the data. The proposed model is supported microscopically by the presence of an alternating component of the g tensor, which produces an internal twofold staggered field that dictates both the direction of the ordered moments and the effective coupling between adjacent chains. The observed magnetic structure is contrary to previous proposals for the departure of the magnitude and field dependence of the energy gap from the predictions of the sine-Gordon model.
More details from the publisher
More details

Spin Dynamics in the Dirac U(1) Spin Liquid YbZn2GaO5

Physical Review Letters American Physical Society (APS) 135:4 (2025) 046704

Authors:

Hank CH Wu, Francis L Pratt, Benjamin M Huddart, Dipranjan Chatterjee, Paul A Goddard, John Singleton, D Prabhakaran, Stephen J Blundell

Abstract:

YbZn 2 GaO 5 is a promising candidate for realizing a quantum spin liquid (QSL) state, particularly owing to its lack of significant site disorder. Pulsed-field magnetometry at 0.5 K shows magnetization saturating near 15 T, with a corrected saturation moment of 2.1 ( 1 ) μ B after subtracting the van Vleck contribution. Our zero-field μ SR measurements down to milliKelvin temperatures provide evidence for a dynamic ground state and the absence of magnetic order. To probe fluctuations in the local magnetic field at the muon site, we performed longitudinal field μ SR experiments. These results provide evidence for spin dynamics with a field dependence that is consistent with a U1A01 Dirac quantum spin liquid as a plausible description of the ground state.
More details from the publisher
More details
More details

A resonant valence bond spin liquid in the dilute limit of doped frustrated Mott insulators

Nature Physics Springer Nature (2025) 1-6

Authors:

Cecilie Glittum, Antonio Štrkalj, Dharmalingam Prabhakaran, Paul A Goddard, Cristian D Batista, Claudio Castelnovo
More details from the publisher
More details
More details

Electron-density analysis of halide⋯halide through-space magnetic exchange

Journal of Applied Crystallography 58:Pt 2 (2025) 363-373

Authors:

R Scatena, ZE Manson, DY Villa, JL Manson, DR Allan, PA Goddard, RD Johnson

Abstract:

We present a combined experimental and density functional theory study that characterizes the charge and spin density in NiX2(3,5-lutidine)4 (X = Cl, Br and I). In this material, magnetic exchange interactions occur via Ni2+-halide⋯halide-Ni2+ pathways, forming one-dimensional chains. We find evidence for weak halide⋯halide covalency in the iodine system, which is greatly reduced when X = Br and is absent for X = Cl; this is consistent with the reported 'switching-on' of magnetic exchange in the larger-halide cases. Our results are benchmarked against density functional theory calculations on [NiHF2(pyrazine)2]SbF6, in which the primary magnetic exchange is mediated by F-H-F bridging ligands. This comparison indicates that, despite the largely depleted charge density found at the centre of halide⋯halide bonds, these through-space interactions can support strong magnetic exchange gated by weak covalency and enhanced by significant electron density overlapping that of the transition metal centres.
More details from the publisher

Magnetic properties of a staggered S=1 chain with an alternating single-ion anisotropy direction

Physical Review B American Physical Society (APS) 111:1 (2025) 014421

Authors:

S Vaidya, SPM Curley, P Manuel, J Ross Stewart, M Duc Le, C Balz, T Shiroka, SJ Blundell, KA Wheeler, I Calderon-Lin, ZE Manson, JL Manson, J Singleton, T Lancaster, RD Johnson, PA Goddard
More details from the publisher
More details

Pagination

  • Current page 1
  • Page 2
  • Page 3
  • Page 4
  • Page 5
  • Page 6
  • Page 7
  • Page 8
  • Page 9
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet