2005/01/31 by J. L. Gavilano, E. Felder, D. Rau +6 · 1 citation
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystallography #Energy (signal processing) #Ising model #Magnetic and transport properties of perovskites and related materials #Magnetic susceptibility #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.064431
10.5 pages, 15 figures. Submitted to Phys. Rev. B
arxiv created 2005/01/31 · openalex publication_date 2005/08/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the results of low-temperature measurements of the specific heat Cp(T), ac susceptibility \ensuremathχac(T) and 23Na nuclear magnetic resonance NMR of Na2V3O7. At liquid He temperatures Cp(T) exhibits a broad field-dependent Schottky-type anomaly. Below 1.5\phantom\rule0.3em0exK the ac magnetic susceptibility \ensuremathχac(T) follows a Curie-Weiss law and exhibits a cusp at 0.086\phantom\rule0.3em0exK which indicates a phase transition at very low temperatures. These results support the previous conjecture that Na2V3O7 is close to a quantum critical point at \ensuremathμ0H\ensuremath≈0\phantom\rule0.3em0exT. The entire data set, including NMR spin-lattice relaxation T\phantom\rule0.1em0ex1^\ensuremath-1(T), reveals a complex magnetic behavior at low temperatures. We argue that it is due to a distribution of singlet-triplet energy gaps of dimerized V moments. The dimerization process evolves over a rather broad temperature range around and below 100\phantom\rule0.3em0exK. At the lowest temperatures the magnetic properties are dominated by the response of only a minor fraction of the V moments.