Interplay of structure and magnetism in ruthenocuprates: a Raman scattering and dilatometry study

FAINSTEIN A, RAMOS CA, PREGLIASCO RG, BUTERA A, TRODAHL HJ, WILLIAMS GVM,

PHYSICA B - CONDENSED MATTER

Año: 2002 vol. 320 p. 322 - 325

0921-4526

We present a Raman scattering and dilatometry study of polycrystalline samples of the magnetic superconducting ruthenocuprates RuSr2Gd2-xCexCu2O10+delta (RuGd1222) and RuSr2GdCu2O8 (RuGd1212). In the Raman spectra a hightemperature diffusive-like laser-tail develops below the magnetic ordering temperature (T-M) into an underdamped peak which shifts up to similar to130 cm(-1). A line assigned to O(Ru) phonons hardens, narrows and strengthens strongly below T-M. Finally, a phonon peak appears below T-M at similar to590 cm(-1). These three magnetic-order-dependent features are observed for RuGd1212 and for RuGd1222 with x = 1.0, but do not appear for x = 0.5. Dilatometry measurements, on the other hand, evidence a change of the expansion coefficient at T-M. These results point to a structural effect accompanying the magnetic order, and suggest a complex interplay of spin and lattice degrees of freedom in these ruthenocuprates. (C) 2002 Elsevier Science B.V. All rights reserved.