182 research outputs found
First-principles investigation of morphotropic transitions and phase-change functional responses in BiFeO3-BiCoO3 multiferroic solid solutions
We present an ab initio study of the BFCO solid solution formed by
multiferroics BiFeO3 (BFO) and BiCoO3 (BCO). We find that BFCO presents a
strongly discontinuous morphotropic transition between BFO-like and BCO-like
ferroelectric phases. Further, for all compositions such phases remain
(meta)stable and retain well-differentiated properties. Our results thus
suggest that an electric field can be used to switch between these structures,
and show that such a switching involves large phase-change effects of various
types, including piezoelectric, electric, and magnetoelectric ones.Comment: Submitte
Ab initio Evidence for Giant Magnetoelectric Responses Driven by Structural Softness
We show that inducing structural softness in regular magnetoelectric (ME)
multiferroics -- i.e., tuning the materials to make their structure strongly
reactive to applied fields -- makes it possible to obtain very large ME
effects. We present illustrative first-principles results for BiFeO3 thin
films.Comment: 4 pages with 3 figures embedded. More information at
http://www.icmab.es/dmmis/leem/jorg
Antiferroelectricity in a family of pyroxene-like oxides with rich polymorphism
Antiferroelectrics have potential applications in energy conversion and
storage, but are scarce, particularly among oxides that otherwise display rich
ferroic behaviours. Are we overlooking potential antiferroelectrics, simply
because we have not discovered their corresponding ferroelectric phase yet?
Here we report a first-principles study suggesting this is the case of a family
ABO pyroxene-like materials, characterized by chains of corner-sharing
BO tetrahedra, a well-known member being KVO. The irregular tetrahedra
have an electric dipole associated to them. In the most stable polymorph, the
dipoles display an antipolar pattern with zero net moment. However, upon
application of an electric field, half of the tetrahedra rotate, flipping the
corresponding dipoles and reaching a ferroelectric state. We discuss the unique
possibilities for tuning and optimization these antiferroelectrics offer. We
argue that the structural features enabling this antiferroelectric behaviour
are also present in other all-important mineral families.Comment: 6 pages, 3 figure
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