Static magnetic order in metallic triangular antiferromagnet Ag2MnO2

Abstract

The magnetic nature of the triangular antiferromagnet Ag2MnO2, which exhibits two magnetic transitions at Tm 1 ∼ 80 K and Tm 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 Tm 1, while zero field (ZF) μ+ SR measurements indicate the existence of static internal magnetic fields below Tm 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 Tm 2. The overall magnetic behavior is therefore clarified in that the static disordered moments appear below Tm 1, whereas the short-range order completes below Tm 2 = TN. © 2008 Elsevier B.V. All rights reserved.