Crystal structure and crystal growth of the polar ferrimagnet CaBaFe4O7

Magnetic materials are a cornerstone for developing spintronic devices for the transport of information via magnetic excitations. To date, relatively few materials have been investigated for the purpose of spin transport, mostly due to the paucity of suitable candidates as these materials are often chemically complex and difficult to synthesize. We present the crystal growth and a structure solution on the high-temperature crystal structure of the layered, polar ferrimagnet ${\mathrm{CaBaFe}}_{4}{\mathrm{O}}_{7}$, which is a possible new contender for spintronics research. The space group is identified as $P3$ by refinement of single crystal and powder neutron diffraction data. At 400 K, the trigonal lattice parameters are $a=11.0114(11)\phantom{\rule{4pt}{0ex}}\AA{}$ and $c=10.330(3)\phantom{\rule{4pt}{0ex}}\AA{}$. The structure is similar to the low-temperature phase with alternating layers of triangular and Kagome-arranged Fe-O tetrahedra. We also present details of the crystal growth by traveling solvent method.