RT Journal Article
SR Electronic
T1 Proof of the elusive high-temperature incommensurate phase in CuO by spherical neutron polarimetry
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaay7661
DO 10.1126/sciadv.aay7661
VO 6
IS 7
A1 Qureshi, Navid
A1 Ressouche, Eric
A1 Mukhin, Alexander
A1 Gospodinov, Marin
A1 Skumryev, Vassil
YR 2020
UL http://advances.sciencemag.org/content/6/7/eaay7661.abstract
AB CuO is the only known binary multiferroic compound, and due to its high transition temperature into the multiferroic state, it has been extensively studied. In comparison to other prototype multiferroics, the nature and even the existence of the high-temperature incommensurate paraelectric phase (AF3) were strongly debated—both experimentally and theoretically—since it is stable for only a few tenths of a kelvin just below the Néel temperature. Until now, there is no proof by neutron diffraction techniques owing to its very small ordered Cu magnetic moment. Here, we demonstrate the potential of spherical neutron polarimetry, first, in detecting magnetic structure changes, which are not or weakly manifest in the peak intensity and, second, in deducing the spin arrangement of the so far hypothetic AF3 phase. Our findings suggest two coexisting spin density waves emerging from an accidental degeneracy of the respective states implying a delicate energy balance in the spin Hamiltonian.