Magnetic ordering in lanthanide-molybdenum oxide nanostructure arrays

Reduced ternary molybdenum oxides, or bronzes, offer an attractive materials platform to study a wide variety of remarkable physical phenomena in a system with highly varied structural chemistry. Interesting electronic behaviors, such as superconductivity, charge density waves, and magnetism, in these materials arise from the strong hybridization of the 4d states of high-valent Mo with O p orbitals. We investigate a series of molybdenum bronze materials with Lanthanide-Mo$_{16}$O$_{44}$ composition that can be described as a three-dimensional array of metallic Mo$_{8}$O$_{32}$ nanostructures computationally predicted to contain a single charge with spin \textonehalf separated by insulating MoO$_{4}$ tetrahedra. This study reveals novel magnetic ordering in Lanthanide-Mo$_{16}$O$_{44}$ systems arising, not from the inclusion of magnetic elements, but rather from an exchange interaction between cubic Mo$_{8}$O$_{32}$ units. Here, we report the magnetometry and transport behaviors of a series of Lanthanide-Mo$_{16}$O$_{44}$ materials, emphasizing an observed low-temperature phase transition signifying the onset of antiferromagnetic ordering between the arrayed nanostructures, and relate these behaviors to their experimentally-characterized structures to reveal the intriguing physics of these correlated electronic systems.