Sr2V3O9 and Ba2V3O9: Quasi-one-dimensional spin-systems with an anomalous low temperature susceptibility

E. E. KAUL; H. ROSNER; V. YUSHANKHAI; J. SICHELSCHMIDT; R. V. SHPANCHENKO; C. GEIBEL

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

The American Physical Society

Año: 2003 vol. 67 p. 1744171 - 17441710

0163-1829

The magnetic behavior of the low-dimensional vanadium oxides Sr2V3O9 and Ba2V3O9 was investigated by means of magnetic susceptibility and specific heat measurements. In both compounds, the results can be very well described by an S = 1/2 Heisenberg antiferromagnetic chain with an intrachain exchange of J = 82 and 94K in Sr2V3O9 and Ba2V3O9, respectively. In Sr2V3O9, antiferromagnetic ordering at TN = 5.3 K indicate a weak interchain exchange of the order of J^ @ 2 K. In contrast, no evidence for magnetic order was found in Ba2V3O9 down to 0.5 K, pointing to an even smaller interchain coupling. In both compounds, we observe a pronounced Curie-like increase of c(T) below 30 K, which we tentatively attribute to a staggered field effect induced by the applied magnetic field. Results of local density approximation calculations support the quasi-one-dimensional character and indicate that in Sr2V3O9, the magnetic chain is perpendicular to the structural one with the magnetic exchange being transferred through VO4 tetrahedra.