Publications by Paul Gregory Freeman

Electron Glass Phase with Resilient Zhang-Rice Singlets in LiCu3O3

László Forró, Rosario Scopelliti, Arnaud Magrez, Krunoslav Prsa, Henrik Moodysson Rønnow, Simon Karl Moser, Jens Christian Johannsen, Paul Gregory Freeman, Edoardo Martino, Gianmarco Gatti

LiCu3O3 is an antiferromagnetic mixed valence cuprate where trilayers of edge -sharing Cu(II)O (3d9) are sandwiched in between planes of Cu(I) (3d10) ions, with Li stochastically substituting Cu(II). Angle resolved photoemission spectroscopy (ARPES) and de ...

Amer Physical Soc2024

Lack of Out-of-Plane Dispersion of the Magnetic Excitations of Charge-Stripe Ordered La2−xSrxNiO4+δ

Paul Gregory Freeman, Alexandra Angeline Turrini

The dependence of the magnetic excitations in the out-of-NiO-plane direction of charge stripe ordered La2-xSrxNiO4+delta x = 0.3 and delta = 0.11 +/- 0.01 were investigated by inelastic neutron scattering. No dispersion was observed for the magnetic excita ...

Physical Soc Japan2022

The instrument suite of the European Spallation Source

Michael Müller, Henrik Moodysson Rønnow, Paul Gregory Freeman, Ursula Bengaard Hansen, Markus Strobl

An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator a ...

2020

Wave Vector Difference of Magnetic Bragg Reflections and Low Energy Magnetic Excitations in Charges-tripe Ordered La2NiO4.11

Paul Gregory Freeman

We report on the magnetism of charge-stripe ordered La2NiO4.11 +/- 0.01 by neutron scattering and mu SR. On going towards zero energy transfer there is an observed wave vector offset in the centring of the magnetic excitations and magnetic Bragg reflection ...

Nature Research2019

Prototype of the novel CAMEA concept-A backend for neutron spectrometers

Henrik Moodysson Rønnow, Paul Gregory Freeman, Felix Groitl, Jakob Lass

2018

Direct evidence for charge stripes in a layered cobalt oxide

Mechthild Enderle, Paul Gregory Freeman, Peter Babkevich

Recent experiments indicate that static stripe-like charge order is generic to the hole-doped copper oxide superconductors and competes with superconductivity. Here we show that a similar type of charge order is present in La-5/Sr-3(1)/3CoO4, an insulating ...

Springer2016

Magnetic phase diagram of La2-xSrxCoO4 revised using muon-spin relaxation

Paul Gregory Freeman

We report the results of a muon-spin relaxation (mu SR) investigation of La2-xSrxCoO4, an antiferromagnetic insulating series which has been shown to support charge ordered and magnetic stripe phases and an hourglass magnetic excitation spectrum. We presen ...

Amer Physical Soc2016

Ba3MxTi3-xO9 (M = Ir, Rh): A family of 5d/4d-based diluted quantum spin liquids

Henrik Moodysson Rønnow, Paul Gregory Freeman

We report the structural and magnetic properties of the 4d (M = Rh) based and 5d ( M = Ir) based systems Ba3MxTi3-xO9 ( nominally x = 0.5, 1). The studied compositions were found to crystallize in a hexagonal structure with the centrosymmetric space group ...

Amer Physical Soc2016

Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba3ZnIr2O9

Henrik Moodysson Rønnow, Martin Mansson, Paul Gregory Freeman

We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba3ZnIr2O9 is a realization of a novel spin-orbital liquid state. Our results reveal that Ba3ZnIr2O9 with Ir5+ (5d(4)) ions and strong spin-orbi ...

2016

Sc2Ga2CuO7: A possible quantum spin liquid near the percolation threshold

Henrik Moodysson Rønnow, Paul Gregory Freeman

Sc2Ga2CuO7 (SGCO) crystallizes in a hexagonal structure (space group: P63/mmc), which can be seen as an alternating stacking of single and double triangular layers. Combining neutron, x-ray, and resonant x-ray diffraction, we establish that the single tria ...

2015

CAMEA ESS - The continuous angle multi-energy analysis indirect geometry spectrometer for the European Spallation Source

Henrik Moodysson Rønnow, Paul Gregory Freeman

The CAMEA ESS neutron spectrometer is designed to achieve a high detection efficiency in the horizontal scattering plane, and to maximize the use of the long pulse European Spallation Source. It is an indirect geometry time-of-flight spectrometer that uses ...

E D P Sciences2015

Jahn-Teller versus quantum effects in the spin-orbital material LuVO3

Mechthild Enderle, Paul Gregory Freeman, Sándor Tóth

We report on combined neutron and resonant x-ray scattering results, identifying the nature of the spin-orbital ground state and magnetic excitations in LuVO3 as driven by the orbital parameter. In particular, we distinguish between models based on orbital ...

American Physical Society2015

Prismatic analyser concept for neutron spectrometers

Henrik Moodysson Rønnow, Martin Mansson, Paul Gregory Freeman

Developments in modern neutron spectroscopy have led to typical sample sizes decreasing from few cm to several mm in diameter samples. We demonstrate how small samples together with the right choice of analyser and detector components makes distance collim ...

American Institute of Physics2014

Development of the magnetic excitations of charge-stripe ordered La2-xSrxNiO4 on doping towards checkerboard charge order

Paul Gregory Freeman

The magnetic excitation spectrums of charge stripe ordered La2-x Sr (x) NiO4 x = 0.45 and x = 0.4 were studied by inelastic neutron scattering. We found the magnetic excitation spectrum of x = 0.45 from the ordered Ni2+ S = 1 spins to match that of checker ...

Korean Physical Soc2013