### Session K20: Focus Session: Multiferroics II - Hexagonal Systems

2:30 PM–5:06 PM, Tuesday, March 14, 2006
Baltimore Convention Center Room: 317

Chair: Alois Loidl, Augsburg University

Abstract ID: BAPS.2006.MAR.K20.1

### Abstract: K20.00001 : Spin-lattice coupling from first principles

2:30 PM–3:06 PM

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#### Author:

Craig Fennie
(Rutgers University)

The hexagonal manganites are a class of multiferroic materials that are simultaneously ferroelectric and antiferromagnetic, in which many physically interesting and potentially technologically relevant manifestations of spin-lattice coupling have been observed. Chromium spinels such as ZnCr$_2$O$_4$ and CdCr$_2$S$_4$ are antiferromagnetic and ferromagnetic insulators respectively, each displaying a differrent manifestation of a spin-lattice effect. In ZnCr$_2$O$_4$ a large magnetically induced phonon anisotropy has been observed while mode-dependant phonon anomalies have been measured in CdCr$_2$S$_4$. With the continuing advances in theoretical algorithms such as the LSDA+U method and in computational power it is now possible to study structurally and magnetically complex solids such as these using density-functional first-principles methods. Here, I describe a first-principles approach to study the influence of magnetic order on the phonons and dielectric properties of YMnO$_3$, ZnCr$_2$O$_4$, and CdCr$_2$S$_4$, our ongoing investigation of the coupling between the magnetic order and polarization in hexagonal manganites, and the search for ferroelectric behaviour in the simple ferromagnet CdCr$_2$S$_4$.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.K20.1