TY - JOUR
KW - Erinaceidae
AU - A.K Yadav
AU - C.T Nelson
AU - S.L Hsu
AU - Z Hong
AU - J.D Clarkson
AU - C.M Schlepuëtz
AU - A.R Damodaran
AU - P Shafer
AU - E Arenholz
AU - L.R Dedon
AU - D Chen
AU - A Vishwanath
AU - A.M Minor
AU - L.Q Chen
AU - J.F Scott
AU - L.W Martin
AU - Ramamoorthy Ramesh
AB - The complex interplay of spin, charge, orbital and lattice degrees of freedom provides a plethora of exotic phases and physical phenomena. In recent years, complex spin topologies have emerged as a consequence of the electronic band structure and the interplay between spin and spin-orbit coupling in materials. Here we produce complex topologies of electrical polarization-namely, nanometre-scale vortex-antivortex (that is, clockwise-anticlockwise) arrays that are reminiscent of rotational spin topologies-by making use of the competition between charge, orbital and lattice degrees of freedom in superlattices of alternating lead titanate and strontium titanate layers. Atomic-scale mapping of the polar atomic displacements by scanning transmission electron microscopy reveals the presence of long-range ordered vortex-antivortex arrays that exhibit nearly continuous polarization rotation. Phase-field modelling confirms that the vortex array is the low-energy state for a range of superlattice periods. Within this range, the large gradient energy from the vortex structure is counterbalanced by the corresponding large reduction in overall electrostatic energy (which would otherwise arise from polar discontinuities at the lead titanate/strontium titanate interfaces) and the elastic energy associated with epitaxial constraints and domain formation. These observations have implications for the creation of new states of matter (such as dipolar skyrmions, hedgehog states) and associated phenomena in ferroic materials, such as electrically controllable chirality. © 2016 Macmillan Publishers Limited. All rights reserved.
BT - Nature
DO - 10.1038/nature16463
LA - eng
M1 - 7589
N1 - cited By 248
N2 - The complex interplay of spin, charge, orbital and lattice degrees of freedom provides a plethora of exotic phases and physical phenomena. In recent years, complex spin topologies have emerged as a consequence of the electronic band structure and the interplay between spin and spin-orbit coupling in materials. Here we produce complex topologies of electrical polarization-namely, nanometre-scale vortex-antivortex (that is, clockwise-anticlockwise) arrays that are reminiscent of rotational spin topologies-by making use of the competition between charge, orbital and lattice degrees of freedom in superlattices of alternating lead titanate and strontium titanate layers. Atomic-scale mapping of the polar atomic displacements by scanning transmission electron microscopy reveals the presence of long-range ordered vortex-antivortex arrays that exhibit nearly continuous polarization rotation. Phase-field modelling confirms that the vortex array is the low-energy state for a range of superlattice periods. Within this range, the large gradient energy from the vortex structure is counterbalanced by the corresponding large reduction in overall electrostatic energy (which would otherwise arise from polar discontinuities at the lead titanate/strontium titanate interfaces) and the elastic energy associated with epitaxial constraints and domain formation. These observations have implications for the creation of new states of matter (such as dipolar skyrmions, hedgehog states) and associated phenomena in ferroic materials, such as electrically controllable chirality. © 2016 Macmillan Publishers Limited. All rights reserved.
PB - Nature Publishing Group
PY - 2016
SP - 198
EP - 201
T2 - Nature
TI - Observation of polar vortices in oxide superlattices
VL - 530
SN - 00280836
ER -