mu SR study of the S=1/2 triangular lattice antiferromagnet AgNiO2

AgNiO2, a model compound of an S = 1/2 triangular lattice, was studied by m uon spin relaxation in addition to ac, dc susceptibility, electrical resist ivity and neutron diffraction. The relaxation rate shows a sharp peak at ar ound T-N = 28 K followed by a sudden decrease of initial asymmetry indicati ng a magnetic ordering. Three internal fields ranging from 0.2 to 0.3 T wer e obtained from the muon precession period. However, a neutron diffraction experiment failed to detect any magnetic order at low temperatures. From th ese results, it was concluded that magnetic coherence is confined to small domain compared with the coherence length of neutron diffraction due to spi n frustration.