Publications by Paolo Radaelli

Modulated spin helicity stabilized by incommensurate orbital density waves in a quadruple perovskite manganite

PHYSICAL REVIEW B 93 (2016) ARTN 180403

RD Johnson, DD Khalyavin, P Manuel, A Bombardi, C Martin, LC Chapon, PG Radaelli

Coherent Magnetoelastic Domains in Multiferroic BiFeO_{3} Films.

Physical review letters 117 (2016) 177601-

N Waterfield Price, RD Johnson, W Saenrang, F Maccherozzi, SS Dhesi, A Bombardi, FP Chmiel, C-B Eom, PG Radaelli

The physical properties of epitaxial films can fundamentally differ from those of bulk single crystals even above the critical thickness. By a combination of nonresonant x-ray magnetic scattering, neutron diffraction and vector-mapped x-ray magnetic linear dichroism photoemission electron microscopy, we show that epitaxial (111)-BiFeO_{3} films support submicron antiferromagnetic domains, which are magnetoelastically coupled to a coherent crystallographic monoclinic twin structure. This unique texture, which is absent in bulk single crystals, should enable control of magnetism in BiFeO_{3} film devices via epitaxial strain.

Polarization memory in the nonpolar magnetic ground state of multiferroic CuFeO2

PHYSICAL REVIEW B 94 (2016) ARTN 144411

J Beilsten-Edmands, SJ Magorrian, FR Foronda, D Prabhakaran, PG Radaelli, RD Johnson

Magnetostriction-driven ground-state stabilization in 2H perovskites

PHYSICAL REVIEW B 94 (2016) ARTN 134404

DG Porter, MS Senn, DD Khalyavin, A Cortese, N Waterfield-Price, PG Radaelli, P Manuel, H-C zur-Loye, C Mazzoli, A Bombardi

Ab initio cycloidal and chiral magnetoelectric responses in Cr2O3

PHYSICAL REVIEW B 94 (2016) ARTN 100405

N Tillack, JR Yates, PG Radaelli

Detailed crystallographic analysis of the ice VI to ice XV hydrogen ordering phase transition.

The Journal of chemical physics 145 (2016) 204501-

CG Salzmann, B Slater, PG Radaelli, JL Finney, JJ Shephard, M Rosillo-Lopez, J Hindley

The D2O ice VI to ice XV hydrogen ordering phase transition at ambient pressure is investigated in detail with neutron diffraction. The lattice constants are found to be sensitive indicators for hydrogen ordering. The a and b lattice constants contract whereas a pronounced expansion in c is found upon hydrogen ordering. Overall, the hydrogen ordering transition goes along with a small increase in volume, which explains why the phase transition is more difficult to observe upon cooling under pressure. Slow-cooling ice VI at 1.4 GPa gives essentially fully hydrogen-disordered ice VI. Consistent with earlier studies, the ice XV obtained after slow-cooling at ambient pressure is best described with P-1 space group symmetry. Using a new modelling approach, we achieve the atomistic reconstruction of a supercell structure that is consistent with the average partially ordered structure derived from Rietveld refinements. This shows that C-type networks are most prevalent in ice XV, but other structural motifs outside of the classifications of the fully hydrogen-ordered networks are identified as well. The recently proposed Pmmn structural model for ice XV is found to be incompatible with our diffraction data, and we argue that only structural models that are capable of describing full hydrogen order should be used.

First-principles study of structurally modulated multiferroic CaMn7O12

PHYSICAL REVIEW B 91 (2015) ARTN 064422

K Cao, RD Johnson, N Perks, F Giustino, PG Radaelli

Theory of Electromagnons in CuO.

Physical review letters 114 (2015) 197201-

K Cao, F Giustino, PG Radaelli

We develop a theory of electromagnons in CuO by combining a symmetry analysis based on irreducible corepresentations, ab initio calculations, and simulations of spin dynamics using a model Hamiltonian and the Landau-Lifshitz-Gilbert equation. We show that the electromagnon measured in [Jones et al., Nat. Commun. 5, 3787 (2014)] with the electric field along the [101] direction originates from a magnetoelectric coupling mediated by Dzyaloshinskii-Moriya interactions and consists of a rigid rotation of the Cu spins around the axis defined by the electric field. Furthermore we predict the existence of a second electromagnon originating from exchange striction and coupled to electric fields along the [010] direction in the AF2 phase.

The contribution of Diamond Light Source to the study of strongly correlated electron systems and complex magnetic structures.

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 373 (2015)

PG Radaelli, SS Dhesi

We review some of the significant contributions to the field of strongly correlated materials and complex magnets, arising from experiments performed at the Diamond Light Source (Harwell Science and Innovation Campus, Didcot, UK) during the first few years of operation (2007-2014). We provide a comprehensive overview of Diamond research on topological insulators, multiferroics, complex oxides and magnetic nanostructures. Several experiments on ultrafast dynamics, magnetic imaging, photoemission electron microscopy, soft X-ray holography and resonant magnetic hard and soft X-ray scattering are described.

Non-ferroelectric nature of the conductance hysteresis in CH3NH3PbI3 perovskite-based photovoltaic devices


J Beilsten-Edmands, GE Eperon, RD Johnson, HJ Snaith, PG Radaelli

Pressure-induced polar phases in multiferroic delafossite CuFeO2

PHYSICAL REVIEW B 89 (2014) ARTN 220403

N Terada, DD Khalyavin, P Manuel, T Osakabe, PG Radaelli, H Kitazawa

Policy: Crystallography needs a governing body.

Nature 505 (2014) 607-609

PG Radaelli

Magnetic and ferroelectric orderings in multiferroic alpha-NaFeO2

PHYSICAL REVIEW B 89 (2014) ARTN 184421

N Terada, DD Khalyavin, JM Perez-Mato, P Manuel, D Prabhakaran, A Daoud-Aladine, PG Radaelli, HS Suzuki, H Kitazawa

Crystallography needs a governing body

Nature 505 (2014) 607-609

PG Radaelli

Diffraction Studies of Multiferroics


RD Johnson, PG Radaelli

Magnetic phase diagram and ordered ground state of GdMn2O5 multiferroic studied by x-ray magnetic scattering


C Vecchini, A Bombardi, LC Chapon, N Lee, PG Radaelli, S-W Cheong, IOP

CaBaCo4O7: A ferrimagnetic pyroelectric

PHYSICAL REVIEW B 90 (2014) ARTN 045129

RD Johnson, K Cao, F Giustino, PG Radaelli

First-principles study of multiferroic RbFe(MoO4)(2)

PHYSICAL REVIEW B 90 (2014) ARTN 024402

K Cao, RD Johnson, F Giustino, PG Radaelli, G-C Guo, L He

Magnetically induced femtoscale strain modulations in HoMn2O5

PHYSICAL REVIEW B 89 (2014) ARTN 125114

C Vecchini, A Bombardi, LC Chapon, G Beutier, PG Radaelli, S Park, S-W Cheong

Giant tunability of ferroelectric polarization in GdMn2O5.

Phys Rev Lett 110 (2013) 137203-

N Lee, C Vecchini, YJ Choi, LC Chapon, A Bombardi, PG Radaelli, S-W Cheong

Giant tunability of ferroelectric polarization (ΔP=5000  μC/m2) in the multiferroic GdMn2O5 with external magnetic fields is discovered. The detailed magnetic model from x-ray magnetic scattering results indicates that the Gd-Mn symmetric exchange striction plays a major role in the tunable ferroelectricity of GdMn2O5, which is in distinction from other compounds of the same family. Thus, the highly isotropic nature of Gd spins plays a key role in the giant magnetoelectric coupling in GdMn2O5. This finding provides a new handle in achieving enhanced magnetoelectric functionality.