​​​​​​​Scientific interests

My scientific research revolves around strongly correlated electron materials. These are systems where the behaviour of the electrons cannot be understood as arising from their motion in an average field due to all the other electrons, but instead depends on the subtle interplay of the spin, charge, orbital and lattice degrees of freedom in the materials. In consequence, the materials can display unexpected ground states with unusual physical properties, properties which in turn can be extremely sensitive to externally applied stimuli such as a magnetic field. It is for these reasons that the study of strongly correlated electron systems is a major theme in condensed matter research. I have a long-running programme studying colossal magnetoresistive manganese oxides, quantum fluctuations in one and two dimensional model magnets, and the spin fluctuations in elemental ferromagnets. In addition, I have also been a member of teams studying iron based and copper oxide high transition temperature superconductors. Highlights from my research and key publications are given further down.

Neutron instrumentation and techniques

Most of my scientific work has been carried out at the ISIS spallation neutron source, where I performed experiments which demonstrated that inelastic neutron scattering from single crystals could be performed highly effectively at pulsed sources, and I was instrumental in establishing the use of time-of-flight techniques with single crystals as a routine probe of magnetic dynamics. I was responsible for the scientific specification and commissioning of the MAPS spectrometer at ISIS, the first time-of-flight neutron spectrometer optimised for measuring excitations in single crystals, and which has been the template for the design of numerous instruments since built at ISIS and other neutron facilities. Over the past few years my efforts have concentrated on maximising the information that can be obtained from the data collected on such instruments through the development of techniques and software to fully map magnetic and lattice dynamics in all four dimensions of wave-vector and energy (http://horace.isis.rl.ac.uk, [1]), as well as software that uses distributed computing to optimise parameters in user-supplied models of the dynamics that fully accounts for the instrumental resolution function (http://tobyfit.isis.rl.ac.uk).

Software

Excitations software home page: click here

Web pages for software projects:

• Visualising and analysing multi-dimensional neutron data: Horace
• Fitting of resolution broadened models to data: Tobyfit

I am a senior scientist at ISIS, conducting a research program in condensed matter physics, and with responsibility for developing techniques and software to study dynamics in single crystals.

Honorary Professor of Physics, London Centre for Nanotechnology, University College London, 2007 – present.

Recipient of the 2003 Willis Prize of the Institute of Physics Neutron Scattering Group.

Scientific highlights

• Colossal magnetoresistive (CMR) manganites. My early work includes the first determination of the spin wave spectrum throughout the Brillouin zone of a CMR manganite [14], the observation of short-range antiferromagnetic fluctuations coexisting with ferromagnetic critical fluctuations [13], and the demonstration of atomic scale stacking of spin valves in a layered manganite [11]. My current interest in colossal magnetoresistive manganites centres on studying the excitations in charge-ordered materials to test the existence or otherwise of magnetic dimers known as Zener polarons [2].
• Quantum magnetism and model magnetic systems in one and two dimensions. Highlights in quantum magnetism include the study of spinons and magnetic form factor in the spin ½ Heisenberg antiferromagnetic chain [4,6], as well as being part of the team that first showed the unambiguous existence of spinons in the Heisenberg antiferromagnet [15]. My current work in quantum magnetism includes attempting to apply quantum infor­mation concepts to one-dimensional systems.
• Itinerant electron ferromagnetism of the elemental transition metals. My renewed interest in the spin dynamics of itinerant electron ferromagnets stems from the development of techniques and software for complete mapping of the dynamics, but the goal of making measurements in these canonical magnets to compare with ab initio calculations dates from the very start of my career [16].
• High temperature superconductivity. I have also been part of long-standing collaborations studying spin dynamics in high transition temperature supercon­ductors. As well my more recent work in studies of the high energy spin dynamics of parents of iron based superconductors [3,5], in earlier years I was a key member of the experimental team in several seminal papers on cuprate superconductors [7,8,10,12].

Key publications

[1] “HORACE: software for the analysis of data from single crystal spectroscopy experiments at time-of-flight neutron instruments”

R.A. Ewings, A. Buts, M.D. Le,  J. van Duijn, I. Bustinduy, T.G. Perring

Nucl. Instrum. Methods. Phys. Res. Sect. A 834, 132 (2016)

 

[2] “Ground State in a Half-Doped Manganite Distinguished by Neutron Spectroscopy”

G.E. Johnstone, T.G. Perring, O. Sikora, D. Prabhakaran, A.T. Boothroyd

Phys. Rev. Lett., 109 237202 (2012)

 

[3] “Itinerant spin excitations in SrFe₂As₂ measured by inelastic neutron scattering”

R.A. Ewings, T.G. Perring, J. Gillett, S.D. Das, S. E. Sebastian, A.E. Taylor, T.Guidi, A.T.  Boothroyd,

Phys. Rev. B 83 214519 (2011)

 

[4] “Effect of covalent bonding on magnetism and the missing neutron intensity in copper oxide compounds”

A.C.Walters, T.G. Perring, J-S Caux, A.T.Savici, G.D.Gu, C.C.Lee, W.Ku, I.A.Zaliznyak

Nature Physics 5 867 (2009)

 

[5] “High-energy spin excitations in BaFe₂As₂ observed by inelastic neutron scattering”

R.A. Ewings, T.G. Perring, R.I. Bewley, T. Guidi, M.J. Pitcher, D.R. Parker, S.J. Clarke, A.T. Boothroyd

Phys. Rev. B 78 220501(R) (2008)

 

[6] “Spinons in the strongly correlated copper oxide chains in SrCuO₂”

I.A.Zaliznyak, H.Woo, T.G.Perring, C.L.Broholm, C.D.Frost, H.Takagi

Phys. Rev. Lett. 93, 087202 (2004)

 

[7] “Quantum Magnetic Excitations from Stripes in Copper-Oxide Superconductors”

J.M.Tranquada, H.Woo, T.G.Perring, H.Goka, G.D.Gu, G.Xu, M.Fujita, K.Yamada

Nature 429, 534 (2004)

 

[8] “The structure of the high-energy spin excitations in a high-transition-temperature superconductor”

S.M.Hayden, H.A.Mook, P.Dai, T.G.Perring, and F.Doğan

Nature 429, 531 (2004)

 

[9] “Spectacular doping dependence of interlayer exchange and other results on spin waves in bilayer manganites”

T.G.Perring , D.T.Adroja, G.Chaboussant, G.Aeppli, T.Kimura, Y.Tokura

Phys. Rev. Lett. 87, 217201 (2001)

 

[10] “Spin waves and electronic interactions in La₂CuO₄”

R.Coldea, S.M.Hayden, G.Aeppli, T.G.Perring, C.D.Frost, T.E.Mason, S-W Cheong, Z. Fisk

Phys. Rev. Lett. 86, 5377 (2001)

 

[11] “Ordered stack of spin valves in a layered magnetoresistive perovskite”

T.G.Perring , G.Aeppli, T.Kimura, Y.Tokura, M.A.Adams

Phys. Rev. B 58, R14693-14696 (1998)

 

[12] “Spin fluctuations in YBa2Cu3O_6.6”

H.A.Mook, P.C.Dai, S.M.Hayden, G.Aeppli, T.G.Perring, F.Dogan

Nature 395, 580 (1998)

 

[13] “Antiferromagnetic short range order in a two-dimensional manganite exhibiting giant magnetoresistance”

T.G.Perring , G.Aeppli, Y.Moritomo, Y.Tokura

Phys. Rev. Lett. 78, 3197 (1997)

 

[14] “Spin-waves throughout the Brillouin-zone of a double-exchange ferromagnet”

T.G.Perring , G.Aeppli, S.M.Hayden, S.A.Carter, J.P.Remeika, S-W Cheong

Phys. Rev. Lett. 77, 711 (1996)

 

[15] “Unbound spinons in the S=1/2 antiferromagnetic chain KCuF₃”

D.A.Tennant, T.G.Perring, R.A.Cowley, S.E.Nagler

Phys. Rev. Lett. 70, 4003 (1993)

 

[16] “High-energy spin-waves in bcc iron”

T.G.Perring , A.T.Boothroyd, D.M.Paul, A.D.Taylor, R.Osborn, R.J.Newport, J.A.Blackman, H.A.Mook

J. Appl. Phys. 69, 6219 (1991)

 

Invited talks at international conferences and workshops since 2010

• Quantum Complex Matter: Superconductivity, magnetism and Ferroelectricity (Stripes 2016) (Ischia, Naples, 23-29 June 2016)
• Electronic Properties of Modern Materials (Abingdon, 17-19 November 2015)
• Chinese Spallation Neutron Source Workshop on Neutron Scattering Instrumentation for Disordered Materials (Dongguan, China,  29-30 June 2015)
• International Conference on Neutron Scattering (ICNS 2013) [Plenary] (Edinburgh, UK, 8-12 July 2013)
• Neutrons 2.0: International Workshop Software for Neutron Scattering (Berlin, Germany, 25-27 March 2013)
• International Conference on Quantum Phenomena in Complex Matter (Stripes 2012) (Erice, Italy, 11-17 July 2012)
• NOBUGS 2012: New Opportunities for Better User Group Software (international Workshop) (STFC, UK, 24-26 September 2012)
• International Workshop on Itinerant Spin-Orbital Systems: From Magnetic Frustration to Novel Superconductivity (Dresden, Germany, 21-25 May 2012)
• 4th UK-Korea workshop on Strongly Correlated Electron Systems (STFC, UK, 12-13 April 2012)
• Frontier Experiments in Quantum Matter (Zermatt, Switzerland, 12-14 March 2012)
• Perspectives in Terahertz Spectroscopy with Neutrons (Berlin, 29-30 November 2011)
• 8^th International Conference on Stripes and High-Tc Superconductivity (Stripes 2011) (Rome, 10-16 July 2011)
• Last DANSE workshop (Distributed Data Analysis for Neutron Scattering Experiments) (Caltech, 4-6 May 2011)
• Neutron Applications on Strongly Correlated Electron Systems 2011 (NASCES11) (Tokai, Japan, 23-25 February 2011)
• 2011 Asia-Pacific Winter Workshop on Frontiers in Electronic Quantum Matter’ (Pohang, Korea, 16-19 February 2011)
• Korea-UK Workshop on Strongly Correlated Electron Systems’ (Seoul, Korea, 14-15 February 2011)
• International Conference on Quantum Phenomena in Complex Matter (Stripes 2010) (Erice, Italy, 19-25 July 2010)
• Workshop on Computational Scattering Science (Argonne National Laboratory, USA, 6-9 July 2010)

In addition, lectures at training schools:

• ‘HERCULES: European school on neutrons and synchrotron radiation for science’, Grenoble (April 2015, April 2016)
• ‘13^th PSI Summer School 2014 on Condensed Matter Research’ (Zug, Switzerland, 10-15 August 2014)
• ‘ISIS and Diamond CDT students’ (Diamond Light Source, March 2015, May 2016)

Membership of scientific committees and panels

Since 2010:

• Member of the European Spallation Source (ESS) Science Advisory Committee (2015-present)
• Member of the Programme Advisory Committee for Condensed Matter Physics at the Joint Institute for Nuclear Research, Dubna, Russia (2014-present)
• Chairman of College 4 sub-committee at Institut Laue Langevin (ILL), Grenoble (2014-present).
• Member of BER-II Reactor Instrument Review Committee at Helmholtz-Zentrum Berlin (HZB) (May 2013).
• Member of neutron scattering Scientific Review Committee at SNS, Oak Ridge (2010-2013).
• Member of Scientific Advisory Panel for the NEAT instrument construction, Helmholtz Centrum Berlin (HZB, Berlin). (2010-present)
• Leader of Spectroscopy Group at ESS Experts meeting to discuss Opportunities in Instrumentation at the European Spallation Source (Vaals, Netherlands, 6-7 September 2010).

Conference International Programme Advisory Committees:

• International Conference on Neutron Scattering (ICNS 2017) (Daejeon, South Korea, July 2017)
• European Conference on Neutron Scattering (ECNS 2015) (Barcelona, August 2015),
• Strongly Correlated Electron Systems Conference (SCES 2012), (South Korea, July 2012)
• Member of Programme Advisory Board for Workshop on Inelastic Neutron Scattering, (Japan, October 2012; Grenoble, May 2014)