Magnetic order in the zigzag-chain antiferromagnet Na2VO(SO4)2

We seek to investigate the formation of long-range magnetic order in the zigzag-chain antiferromagnet Na2VO(SO4)2, where helical order should arise from the competition between ferromagnetic nearest-neighbor (J1) and antiferromagnetic next-nearest-neighbor (J2) couplings along the spin chains. Using muons as a sensitive probe of local magnetic fields, we want to detect long-range magnetic order in Na2VO(SO4)2 and determine the Neel temperature, which is needed for planning the neutron experiments. Additionally, the presence of several oscillation frequencies in the ordered state will support our conjecture on the incommensurate (helical) magnetic structure. This will establish Na2VO(SO4)2 as a reference system for isotypic but more complex vanadium-based materials, such as beta-TeVO4 with its enigmatic sequence of magnetic transitions and two different helixplanes within one structure.