Structural evolution and skyrmionic phase diagram of the lacunar spinel <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">GaMo</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Se</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:math>
Emily C. Schueller, Daniil A. Kitchaev, Julia L. Zuo, Joshua D. Bocarsly, Joya A. Cooley, Anton Van der Ven, Stephen D. Wilson, Ram Seshadri
Abstract
The lacunar spinel family, which contains multiferroic skyrmion hosts GaV4S${}_{8}$ and GaV${}_{4}$Se${}_{8}$, is characterized by unique metal--metal bonding leading to strong coupling between crystal structure and magnetism. Synchrotron diffraction analysis of the low temperature crystal structure of GaMo${}_{4}$Se${}_{8}$, a less studied member of the family, reveals coexistence of the reported rhombohedral crystal structure and a new metastable orthorhombic structure. Computational and experimental characterization of the magnetic phase diagram of GaMo${}_{4}$Se${}_{8}$ indicates that slight crystal structure differences lead to distinct magnetic properties; the reported $R3m$ phase hosts skyrmions similar to GaV${}_{4}$Se${}_{8}$, while the novel $I\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}m2$ phase is a strongly uniaxial ferromagnet.