Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Correlated Electrons: Spin Systems and Itinerant Magnets – Frustrated Magnets 3 (jointly with MA)
TT 30.1: Vortrag
Dienstag, 17. März 2015, 09:30–09:45, H 0110
Collinear order in the frustrated spin-1/2 antiferromagnet Li2CuW2O8 — •Alexander A. Tsirlin1, Ramesh Nath2, Kumar Ranjith2, Deepa Kasinathan3, and Markos Skoulatos4 — 1NICPB, Tallinn, Estonia — 2Indian Institute of Science Education and Research, Trivandrum, India — 3MPI CPfS, Dresden, Germany — 4Laboratory of Neutron Scattering, PSI, Villigen, Switzerland
Li2CuW2O8 is a three-dimensional spin-1/2 antiferromagnet that features collinear spin order despite abundant magnetic frustration that would normally trigger a non-collinear incommensurate order, at least on the classical level. Using density-functional calculations, we establish the spin lattice comprising two non-coplanar triangular networks that introduce frustration along all three crystallographic directions. Magnetic susceptibility and heat capacity reveal a 1D-like magnetic response, which is, however, inconsistent with the naive spin-chain model. Moreover, the high saturation field of 29 T compared to the susceptibility maximum at as low as 8.5 K give strong evidence for the importance of interchain couplings and the magnetic frustration. Below TN≃ 3.9 K, Li2CuW2O8 develops collinear magnetic order with parallel spins along a and c and antiparallel spins along b. The ordered moment is about 0.7 µB according to neutron powder diffraction. This qualifies Li2CuW2O8 as a unique three-dimensional spin-1/2 antiferromagnet, where collinear magnetic order is stabilized by quantum fluctuations.
Financial support of the Mobilitas program (ESF) is acknowledged.