Static magnetic order in metallic triangular antiferromagnet Ag2MnO2

Abstract The magnetic nature of the triangular antiferromagnet Ag 2 MnO 2 , which exhibits two magnetic transitions at T m 1 ∼ 80 K and T m 2 ∼ 30 K , 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 T m 1 , while zero field (ZF) μ + SR measurements indicate the existence of static internal magnetic fields below T m 2 . 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 T m 2 . The overall magnetic behavior is therefore clarified in that the static disordered moments appear below T m 1 , whereas the short-range order completes below T m 2 = T N .