Job Title
LET Instrument Scientist
Office Phone Number
Office Location
Mobile Phone Number

​​​​​​Research Interests

​Structure and dynamics of frustrated magnetic materi​​​als​​

Frustrated magnets are fascinating model systems in which the lattice topology and/or mixed magne​​tic interactions can lead to an extensively degenerate magnetic ground state. This leads to novel magnetic structural and dynamical properties in these materials.  Ross has, over the years, investigated various metallic frustrated magnets (β-Mn, YMn2, INVAR) mainly using neutron polarization analysis,  inelastic neutron scattering and muon spin relaxation (μSR) techniques. He is also interested in the magnetic structural and dynamical properties of antiferromagnetic pyrochlore lattices (Gd2Ti2O7, Gd2Sn2O7) and kagome lattice (herbertsmithite, swedenborgite) materials. This work is done in collaboration with  Dr Joe Paddison (ORNL) and Dr. Andrew Goodwin (Oxford), addition to various other UK and international research teams.

Selected Publications:

J A M Paddison, G Ehlers, A B Cairns, J S Gardner, O A Petrenko, N P Butch, D D Khalyavin, P Manuel, H E Fischer, A L Goodwin, and J R Stewart. Suppressed-moment 2-k order in the canonical frustrated antiferromagnet Gd2Ti2O7
npj Quantum Materials6 99 (2021)

J A M Paddison, G Ehlers, O A Petrenko, A R Wildes, J S Gardner, and J R Stewart
Spin correlations in the dipolar pyrochlore antiferromagnet Gd2Sn2O7
J. Phys.: Condens. Matter 29 144001 (2017)

J A M Paddison, J R Stewart, P Manuel, P Courtois, G J McIntyre, B D Rainford, and A L Goodwin
Emergent Frustration in Co-doped beta-Mn
  • Phys. Rev. Lett. 110 267207 (2013)

G J Nilsen, M A De Vries, J R Stewart, A Harrison, and H M Ronnow
Low energy spin dynamics of the s=1/2 kagome system volborthite 

Polarized Neutron Sca​​tte​​ring

Between 1998 and 2008, Ross worked at the Institut Laue-Langevin in Grenoble, where he led the redesign and reconstruction of the diffuse scattering spectrometer, D7, as part of the ILL Millennium Programme.   He designed a novel supermirror spin-analyser array for D7 which provided a factor of 60 increase in count-rate of this instrument.  At ISIS, from 2010-2017 Ross led the projects to bring 3He MEOP spin-filters to beamlines such as LARMOR and LET.  The LET spectrometer has recently been equiped with neut​ron polarization analysis using a combination of a supermirror polarizer and 3He wide-angle analyser system.  First experiments are now being performed, and Ross now provides experimental support.  

Selected Publications:

  • A. Arbe, G J Nilsen, J R Stewart, F Alvarez, V Garcia Sakai and J Colmenero

    Coherent structural relaxation of water from meso- to intermolecular scales measured using neutron spectroscopy with polarization analysis. 

    Phys. Rev. Research 2022015(R) (2020)

  • J R Stewart, S R Giblin, D Honecker, P Fouquet, D Prabhakaran, and J W Taylor
    • Transverse and longitudinal spin-fluctuations in INVAR Fe0.65Ni0.35​​
    • J. Phys.: Condens. Matter 31 025802 (2019)
    • 10.1088/1361-648X/aaeeaf
G Ehlers, J R Stewart, A R Wildes, P P Deen, and K H Andersen
alization of the classical xyz-polarization analysis technique to out-of-plane and inelastic scattering
Rev. Sci. Instrum84 093901 (2013)
2013 | journal-article

J R Stewart, P P Deen, K H Andersen, H Schober, J-F Barth ́el ́emy, J M Hillier, A P Murani, T Hayes, and B Lindenau
Disordered materials studied using neutron polarization analysis on the multi-detector spectrometer, D7
J. Appl. Cryst. 42 69–84 (2009)

Co-funded Rese​arch Students​​​​​​​​​

  • ​​​​​​Philip Welch (University of Oxford) 2015-2021
  • Toby Willis (Royal Holloway) 2013-2016
  • Joe Paddison (Univeristy of Oxford) 2012-2016
  • Giovanni Pasquino (Royal Holloway) 2011-2015
  • Clare Leavey (University of Southampton) 2004-2008
  • Judith Preston (University of Leeds) 1999-2002
  • Charlotte Anderson (University of Liverpool) 1998-1999​​

​​External B​​o​​​​die​​s​

  • ​​​​Chair: IOP/RSC UK Neutron Scattering Group
  • Editorial board: J. Phys: Condens. Matter (Magnetism section)
  • Member of the Institute of Physics (CPhys MInstP)