Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 78: Correlated Electrons: Poster Session

TT 78.28: Poster

Donnerstag, 10. März 2016, 15:00–18:30, Poster D

Fragmented S=1/2 alternating spin chains in layered monoclinic Li₃Cu₂SbO₆ — •Michael Richter¹, Changhyun Koo¹, Vladimir Nalbandyan², Elena Zvereva³, Alexander Vasiliev³, Igor Shukaev², and Rüdiger Klingeler¹ — ¹Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany — ²Chemistry Faculty, Southern Federal University, Rostov-na-Donu, Russia — ³Faculty of Physics, Moscow State University, Moscow, Russia

We report the magnetic properties of polycrystalline layered Li₃Cu₂SbO₆ which reveals the coexistence of alternating S=1/2 spin chains, spin chain fragments and quasi-free spins. Static magnetic susceptibility measurements show two contributions to the magnetic response, namely quasi-free spins at low-temperature and a spin-gapped magnetic subsystem with Δ ∼ 120 K. Quantitatively, the data imply that about half of the spins are organized in alternating Heisenberg chains with J₁ = 75 K and J₂/J₁ = 0.6. Our X-band ESR data corroborate well with this analysis by indicating three resolved resonance modes. High-frequency ESR shows powder-like spectra which are well described by an anisotropic g-factor with g_|| = 2.31 and g_⊥ = 2.05. The magnetic response is ascribed to significant antisite disorder between Li and Cu-sites which yields quasi-free S=1/2 spins at Li-sites as well as fragmentation of the spin chains in the Cu-layers.