A TM-169 MOSSBAUER INVESTIGATION OF TM2CU2O5

A Tm-169 Mossbauer investigation of Tm2Cu2O5 is reported. All spectra over the temperature range 4.2-300 K are able to be analysed in terms of a single Tm site even though there are known to be 2 non-equivalent Tm sites for the Ho2Cu2O5-type structure. The Tm lattice is determined to be magnetically polarised below T(order) = 17.5 K with a site-independent moment of mu(Tm) = 3.90(8)mu(B) at 4.2 K. A 2-singlet model is proposed wherein the Tm moments are induced by a molecular field which is proportional to the Cu magnetisation. The model is consistent with canted Tm magnetism and estimates a saturation molecular field of 1.65 T to act at each Tm atom.