Magnetic ordering process in diluted Ising spin nets, Rb2CocMg1−cF4, probed by muon spin relaxation

Abstract Muon spin relaxation was measured on Rb 2 Co c Mg 1− c F 4 to study magnetic ordering and spin fluctuations in diluted Ising spin nets with concentration near the percolation threshold, c p =0.593. In a c =0.6 compound, the μSR spectrum shows a distinct anomaly due to the long-range ordering of the fractal lattice at 31 K much higher than T N =20 K . Comparing with the results for a c =0.5 compound, the observed spectra for the c =0.6 compound are analysed in terms of the spin fluctuations of the fractal lattice and the isolated spin clusters which are frozen gradually below 15 K.