부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solidstatesciences.2005.04.011 Byline: M. BaAanda (a), T. Korzeniak (b), R. PeAka (a), R. Podgajny (b), M. Rams (c), B. Sieklucka (b), T. WasiutyAski (a) Keywords: AC susceptibility; Molecular magnet; Layered system; Critical exponent; Copper octacyanometallate; Hopkinson effect Abstract: AC susceptibility, I.sub.AC, for ferromagnetic Cu.sup.II[W.sup.V(CN).sub.8]- and Cu.sup.II[Mo.sup.V(CN).sub.8]-based molecular magnets with T.sub.C[approximately equal to]30K of the unique bilayered structure is investigated. I.sub.AC(T) is measured with different frequency and amplitude of the oscillating field for various magnitudes of static applied field. Cu.sup.II[W.sup.V(CN).sub.8]-based compounds show a sharp anomaly at the transition and extremely low effect below T.sub.C; second harmonic of I.sub.AC and DC magnetization curves suggest some weak antiferromagnetic interactions while critical behaviour points to the Ising anisotropy in these samples. Susceptibility of these compounds is strongly enhanced by applying DC field of about 50 Oe. For the Cu.sup.II[Mo.sup.V(CN).sub.8]-based compounds I.sub.AC is more typical and the critical exponent [gamma] is close to that of 3D Heisenberg magnets. It is suggested that the different behaviour of these isostructural and isospin compounds is related to the more diffuse 5d shell of tungsten centres that may enhance the possible antiferromagnetic exchange through the CN-bridges. At H.sub.DC=0 there is almost no frequency dependence of I.sub.AC. Weak glass-like character of tungstate compounds which appears in the applied field is probably due to random weak interactions through the hydrogen bonds disordered in the space between the bilayers and random anisotropy coming from the countercations. Author Affiliation: (a) H. NiewodniczaAski Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Krakow, Poland (b) Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland (c) Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland Article History: Received 17 October 2004; Revised 12 January 2005; Accepted 25 April 2005