MU-SR INVESTIGATION OF CUPRIC OXIDE

TF and ZF muSR-investigations were performed on high purity CuO powder . By TF measurements a phase transition to the ordered state was obser ved at 227K. A commensurate-incommensurate phase transition was detect ed at 213K by ZF measurements. In the commensurate phase we observed t he Larmor precession. Four signals were detected below 55K, but by inc reasing temperature above 190K, precession became having only one comp onent. This fact may be explained by muons tunneling between equivalen t sites. In the incommensurate phase the Larmor precession was not det ected because, of too large damping.