μSR studies of two-dimensional antiferromagnets CaV3O7 and SrV3O7

A discontinuous change of muon-spin precession frequencies in CaV3O7 is observed at T∼0.2K, indicating a possible spin reorientation. Our results suggest that CaV3O7 possesses the identical spin direction as isostructural SrV3O7 below ∼0.2K, although the spin directions in the two compounds are different at higher temperatures as determined by elastic neutron scattering.