2H-perovskite related oxides: Synthesis, structures, and predictions

Abstract

The ability to synthesize new complex oxide materials that belong to any of the large number of known oxide structural families relies typically on a general understanding of the relationship between the specific structure type and the chemical composition of its members. However, before one can create such a structure-composition relationship that enables the synthesis of new members, one needs structural information about a sizable number of existing compositions belonging to this structural family, somewhat of a ''chicken or the egg'' problem. In this Highlight we will use one family of oxides, specifically oxides related to the hexagonal perovskite structure, to illustrate how exploratory crystal growth methods have been used successfully to synthesize enough diverse compositions to enable the formulation of a general structural description. Furthermore, by now it appears that enough members with different compositions have been synthesized so that one can attempt to create a structurecomposition relationship that has predictive powers.

Magnetostriction-driven ground-state stabilization in 2H perovskites

“…Measurements were performed at the Ru L 3 absorption edge (2.838 keV) by reconfiguring the beamline for low energies, performing four bounces on the silicon monochromator, minimizing the air path, and extending the detector capability to low energies. At this energy, the focused spot size was ≈ 180 × 50 μm 2 . This is notably the first experiment on I16 in this energy range, effectively extending the beamline capability below the initial specifications.…”

“…Samples were aligned in different geometries depending on the reflections measured. For reflections along the 00L direction, the samples were mounted as vertical rods, scattering from a very small 50 × 50 μm 2 , cleaved surface at the top of the rod. This arrangement gave access to reflections close to the 00L direction and had the advantage of providing a large azimuthal range at the (003) reflection.…”

“…In this peculiar arrangement, magnetic ions sit within the octahedra, the trigonal prism or at both sites, offering a fertile ground for the investigation of a range of phenomena. For instance, diluting the trigonal prisms along the c axis with varying the m/n ratio leads to valence disproportionations [1], whereas the arrangement in chains can be readily connected with dimensionality effects [2]. In this paper we will focus on systems with m = 0 and n = 1, adopting the trigonal R3c structure illustrated in Fig.…”

“…It couples the out-of-plane ferromagnetic component μ in the case of the (η 1 ,0) order-parameter direction (C2 /c symmetry) and it vanishes for the (0,η 2 ) direction (C2/c symmetry). To understand which microscopic interactions are behind this energy term, let us rewrite the nonvanishing part δμη as δμηη 2 . The latter includes the product of μ (ferromagnetic) and η (antiferromagnetic) order parameters as in the case of antisymmetric DM exchange interactions.…”

Magnetic properties ofSr3NiIrO6andSr3CoIrO6: Magnetic hysteresis with coercive fields of up to 55 T

“…This large hysteresis evolves out of a frustrated, antiferromagnetic ground state that incorporates an entangled spin-orbit state on the 5d ion [10]. Sr 3 NiIrO 6 and Sr 3 CoIrO 6 are members of the A 3 BB O 6 family, where A is an alkaline earth and B and B are transition metal ions [11]. Soon after their synthesis [12], it was realized [13,14] that the interplay of electron correlations, magnetic frustration, reduced dimensionality, and magnetocrystalline anisotropy could lead to interesting physics; subsequently the structural and magnetic properties have been the subject of several studies (e.g., Refs.…”