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Magnetic structure and spin dynamics of the quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Kawasaki Y, Gavilano JL, Keller L, Schefer J, Christensen NB, Amato A, Ohno T, Kishimoto Y, He ZZ, Ueda Y, Itoh M,
Project Interplay of Magnetism and Superconductivity in Unconventional Superconductors
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Original article (peer-reviewed)

Journal PHYSICAL REVIEW B
Volume (Issue) 83(6)
Page(s) 064421-1 - 064421-6
Title of proceedings PHYSICAL REVIEW B
DOI 10.1103/PhysRevB.83.064421

Abstract

We report a neutron diffraction and muon spin relaxation μSR study of static and dynamical magnetic properties of BaCo2 V2 O8 , a quasi-one-dimensional spin-chain system. A proposed model for the antiferromagnetic structure includes: a propagation vector k⃗AF = (0,0,1), independent of external magnetic fields for fields below a critical value Hc (T ). The ordered moments of 2.18 μB per Co ion are aligned along the crystallographic c axis. Within the screw chains, along the c axis, the moments are arranged antiferromagnetically. In the basal planes the spins are arranged ferromagnetically (forming zigzag paths) along one of the axes and antiferromagnetically along the other. The temperature dependence of the sublattice magnetization is consistent with the expectations of the three-dimensional (3D) Ising model. A similar behavior is observed for the internal static fields at different muon stopping sites. Muon time spectra measured at weak longitudinal fields and temperatures much higher than TN can be well described using a single muon site with an exponential muon spin relaxation that gradually changes into an stretched exponential on approaching TN . The temperature-induced changes of the relaxation suggest that the Co fluctuations dramatically slow down and the system becomes less homogeneous as it approaches the antiferromagnetic state.
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