Momentum-resolved observations of the phonon instability driving geometric improper ferroelectricity in yttrium manganite.

Title Momentum-resolved observations of the phonon instability driving geometric improper ferroelectricity in yttrium manganite.
Authors D. Bansal; J.L. Niedziela; R. Sinclair; O. Garlea; D.L. Abernathy; S. Chi; Y. Ren; H. Zhou; O. Delaire
Journal Nat Commun
DOI 10.1038/s41467-017-02309-2
Abstract

Magnetoelectrics offer tantalizing opportunities for devices coupling ferroelectricity and magnetism but remain difficult to realize. Breakthrough strategies could circumvent the mutually exclusive origins of magnetism and ferroelectricity by exploiting the interaction of multiple phonon modes in geometric improper and hybrid improper ferroelectrics. Yet, the proposed instability of a zone-boundary phonon mode, driving the emergence of ferroelectricity via coupling to a polar mode, remains to be directly observed. Here, we provide previously missing evidence for this scenario in the archetypal improper ferroelectric, yttrium manganite, through comprehensive scattering measurements of the atomic structure and phonons, supported with first-principles simulations. Our experiments and theoretical modeling resolve the origin of the unusual temperature dependence of the polarization and rule out a reported double-step ferroelectric transition. These results emphasize the critical role of phonon anharmonicity in rationalizing lattice instabilities in improper ferroelectrics and show that including these effects in simulations could facilitate the design of magnetoelectrics.

Citation D. Bansal; J.L. Niedziela; R. Sinclair; O. Garlea; D.L. Abernathy; S. Chi; Y. Ren; H. Zhou; O. Delaire.Momentum-resolved observations of the phonon instability driving geometric improper ferroelectricity in yttrium manganite.. Nat Commun. 2018;9(1):15. doi:10.1038/s41467-017-02309-2

Related Elements

Manganese

See more Manganese products. Manganese (atomic symbol: Mn, atomic number: 25) is a Block D, Group 7, Period 4 element with an atomic weight of 54.938045. Manganese Bohr ModelThe number of electrons in each of Manganese's shells is [2, 8, 13, 2] and its electron configuration is [Ar] 3d5 4s2. The manganese atom has a radius of 127 pm and a Van der Waals radius of 197 pm. Manganese was first discovered by Torbern Olof Bergman in 1770 and first isolated by Johann Gottlieb Gahn in 1774. In its elemental form, manganese has a silvery metallic appearance. Elemental ManganeseIt is a paramagnetic metal that oxidizes easily in addition to being very hard and brittle. Manganese is found as a free element in nature and also in the minerals pyrolusite, braunite, psilomelane, and rhodochrosite. The name Manganese originates from the Latin word mangnes, meaning "magnet."

Yttrium

See more Yttrium products. Yttrium (atomic symbol: Y, atomic number: 39) is a Block D, Group 3, Period 5 element with an atomic weight of 88.90585. Yttrium Bohr ModelThe number of electrons in each of yttrium's shells is [2, 8, 18, 9, 2] and its electron configuration is [Kr] 4d1 5s2. The yttrium atom has a radius of 180 pm and a Van der Waals radius of 219 pm. Yttrium was discovered by Johann Gadolin in 1794 and first isolated by Carl Gustav Mosander in 1840. In its elemental form, Yttrium has a silvery white metallic appearance. Yttrium has the highest thermodynamic affinity for oxygen of any element. Elemental YttriumYttrium is not found in nature as a free element and is almost always found combined with the lanthanides in rare earth minerals. While not part of the rare earth series, it resembles the heavy rare earths which are sometimes referred to as the "yttrics" for this reason. Another unique characteristic derives from its ability to form crystals with useful properties. The name yttrium originated from a Swedish village near Vaxholm called Yttbery where it was discovered.

Related Forms & Applications