Static magnetic order in metallic triangular antiferromagnet Ag2MnO2

The magnetic nature of the triangular antiferromagnet Ag2MnO2, which exhibits two magnetic transitions at Tm1∼80K and Tm2∼30K, has been studied with μ+SR spectroscopy using a polycrystalline sample in the temperature (T) range between 300 and 1.8 K. Weak transverse field muon-spin rotation and relaxation (μ+SR) measurements suggest the appearance of a random internal magnetic field at T below Tm1, while zero field (ZF) μ+SR measurements indicate the existence of static internal magnetic fields below Tm2. Furthermore, two components with ∼10 times different precession frequencies but almost equivalent amplitudes in the ZF-spectrum indicate the formation of a static but complex antiferromagnetic order below Tm2. The overall magnetic behavior is therefore clarified in that the static disordered moments appear below Tm1, whereas the short-range order completes below Tm2=TN.