Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Low-dimensional Systems - Materials 2
TT 28.3: Talk
Wednesday, March 28, 2012, 15:30–15:45, H 0104
Magnetic properties of alternating spin-1/2 chain compound AgVOAsO4 — •Ramesh Nath1, Alexander Tsirlin2, Panchanana Khuntia2, Michael Baenitz2, Yurii Skourski3, Christoph Geibel2, and Helge Rosner2 — 1School of Physics, IISER, Thiruvananthapuram-695016 Kerala, India — 2MPI CPfS, Nothnitzer Str. 40, 01187 Dresden, Germany — 3HLD, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany
We investigate the magnetic properties of a one-dimensional (1D) spin-1/2 alternating chain compound AgVOAsO4 via magnetic susceptibility, high-field magnetization, and 75As NMR measurements. Temperature dependence of the magnetic susceptibility (χ(T)) and NMR shift (K(T)) were fitted well by the expression for the 1D spin-1/2 alternating chain. The exchange couplings along the chain are estimated to be J ≃ 40 K and J′ ≃ 25 K, with a spin gap Δ ≃13 K. The high-field magnetization measurement at 1.4 K confirms the ground state to be a non-magnetic singlet, and reveals the critical field Hc ≃ 10 T of the gap closing and a saturation field µ0Hs ≃ 48.5 T. These values are largely consistent with the estimated Δ and (J, J′) values based on the fit of χ(T) and K(T). The 75As spin-lattice relaxation rate (1/T1) follows an activated behavior at low temperatures giving rise to the same Δ value. Our experimental investigations are supported by band structure calculations that additionally reveal weak and frustrated interchain couplings, thus making this compound a promising candidate for Bose-Einstein condensation of magnons in high magnetic fields.