Professor Paolo G. Radaelli OSI: Publications

Prof Radaelli recognised with an MPLS "Excellent Supervisor" Award

Prof Radaelli is one of the 5 91̽�� Physicists recognised in the inaugural "Excellence in Research Supervision" award

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Electric field control of the magnetic chiralities in ferroaxial multiferroic RbFe(MoO4)2

ArXiv 1202.2317 (2012)

Authors:

Alexander J Hearmon, Federica Fabrizi, Laurent C Chapon, RD Johnson, Dharmalingam Prabhakaran, Sergey V Streltsov, PJ Brown, Paolo G Radaelli

Abstract:

The coupling of magnetic chiralities to the ferroelectric polarisation in multiferroic RbFe(MoO$_4$)$_2$ is investigated by neutron spherical polarimetry. Because of the axiality of the crystal structure below $T_\textrm{c}$ = 190 K, helicity and triangular chirality are symmetric-exchange coupled, explaining the onset of the ferroelectricity in this proper-screw magnetic structure - a mechanism that can be generalised to other systems with "ferroaxial" distortions in the crystal structure. With an applied electric field we demonstrate control of the chiralities in both structural domains simultaneously.

Spin waves and revised crystal structure of honeycomb iridate Na2IrO3

(2012)

Authors:

SK Choi, R Coldea, AN Kolmogorov, T Lancaster, II Mazin, SJ Blundell, PG Radaelli, Yogesh Singh, P Gegenwart, KR Choi, S-W Cheong, PJ Baker, C Stock, J Taylor

Helical scattering signatures of strain and electronic textures in YbFe2O4 from three-dimensional reciprocal-space imaging

Physical Review B American Physical Society (APS) 85:1 (2012) 014115

Authors:

Alexander J Hearmon, Dharmalingam Prabhakaran, Harriott Nowell, Federica Fabrizi, Matthias J Gutmann, Paolo G Radaelli

Helical scattering signatures of strain and electronic textures in YbFe₂O₄ from three-dimensional reciprocal-space imaging

PHYSICAL REVIEW B 85:1 (2012) ARTN 014115

Authors:

Alexander J Hearmon, Dharmalingam Prabhakaran, Harriott Nowell, Federica Fabrizi, Matthias J Gutmann, Paolo G Radaelli

Magneto-orbital helices as a route to coupling magnetism and ferroelectricity in multiferroic CaMn₇O₁₂.

Nat Commun 3 (2012) 1277

Authors:

NJ Perks, RD Johnson, C Martin, LC Chapon, PG Radaelli

Abstract:

Orbital physics drives a rich phenomenology in transition-metal oxides, providing the microscopic underpinning for effects such as Colossal Magnetoresistance. In particular, magnetic and lattice degrees of freedom are coupled through orbital ordering, and it has long been hoped that this coupling could be exploited to create high-temperature multiferroics with large values of the electrical polarization. Here we report an unprecedented magneto-orbital texture in multiferroic CaMn(7)O(12), found to give rise to the largest magnetically induced ferroelectric polarization measured to date. X-ray diffraction characterization of the structural modulation in these 'magneto-orbital helices', and analysis of magnetic exchange shows that orbital order is crucial in stabilising a chiral magnetic structure, thus allowing for electric polarization. Additionally, the presence of a global structural rotation enables the coupling between this polarization and magnetic helicity required for multiferroicity. These novel principles open up the possibility of discovering new multiferroics with even larger polarization and higher transition temperatures.

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