Interplay between structural, electronic, and magnetic degrees of freedom in Sr(3)Cr(2)O(8)

We present a theoretical investigation of the orbital ordering occurring in Sr(3)Cr(2)O(8) based on density functional theory calculations. We demonstrate that the strong electron correlation arising within the Cr-3d shell can clearly explain both the phase transition leading to the stabilization of its monoclinic C2/c space-group symmetry and its spin-singlet magnetic ground state. The relevance of the electronic structure determined theoretically is further established by comparison to high-resolution electron energy loss spectroscopy measurements.

Singlet-triplet dispersion reveals additional frustration in the triangular-lattice dimer compound Ba3Mn2O8

We present single crystal inelastic neutron scattering measurements of the S=1 dimerized quasi-two-dimensional antiferromagnet Ba(3)Mn(2)O(8). The singlet-triplet dispersion reveals nearest-neighbor and next-nearest-neighbor ferromagnetic interactions between adjacent bilayers that compete against each other. Although the interbilayer exchange is comparable to the intrabilayer exchange, this additional frustration reduces the effective coupling along the c axis and leads to a quasi-two-dimensional behavior. In addition, the obtained exchange values are able to reproduce the four critical fields in the phase diagram.