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

TL;DR

This study investigates the magnetic properties of Sr2V3O9 and Ba2V3O9, revealing their behavior as quasi-one-dimensional spin systems with unique low-temperature susceptibility features and weak interchain interactions.

Contribution

It provides detailed experimental and theoretical analysis of the magnetic behavior of Sr2V3O9 and Ba2V3O9, highlighting their quasi-one-dimensional nature and anomalous susceptibility at low temperatures.

Findings

Both compounds behave as S=1/2 Heisenberg antiferromagnetic chains.

Sr2V3O9 shows antiferromagnetic order at 5.3 K, Ba2V3O9 does not down to 0.5 K.

Pronounced Curie-like increase in susceptibility below 30 K.

Abstract

The magnetic behaviour 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 K and J = 94 K in Sr2V3O9 and Ba2V3O9, respectively. In Sr2V3O9, antiferromagnetic ordering at T_N = 5.3 K indicate a weak interchain exchange of the order of J_perp ~ 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 the susceptibility below 30 K, which we tentatively attribute to a staggered field effect induced by the applied magnetic field. Results of LDA 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.