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Title: Antiferromagnetic spin structure and negative thermal expansion of Li2Ni(WO4)2
Authors: Karna, SK
Wang, CW
Sankar, R
Avdeev, M
Singh, A
Panneer Muthuselvam, I
Singh, VN
Guo, GY
Chou, FC
Keywords: Antiferromagnetism
Thermal expansion
Neutron diffraction
Crystal structure
Magnetic moments
Issue Date: 10-Jul-2015
Publisher: American Physical Society
Citation: Karna, S. K., Wang, C. W., Sankar, R., Avdeev, M., Singh, A., Panneer Muthuselvam, I., Singh, V. N., Guo, G. Y., & Chou, F. C. (2015). Antiferromagnetic spin structure and negative thermal expansion of Li2Ni(WO4)2. Physical Review B, 92(1), 014413. doi:10.1103/PhysRevB.92.014413
Abstract: We report the results of a study on the crystal and magnetic structure of Li2Ni(WO4)2 with a neutron diffraction technique. The Ni2+ spins of S = 1 for NiO6 octahedra are coupled via corner-sharing, nonmagnetic double tungstate groups in a super-superexchange route. Two magnetic anomalies at TN1∼ 18 K and TN2∼ 13 K are revealed from the measured magnetic susceptibility χ(T), and TN2 is confirmed to be the onset of a commensurate long-range antiferromagnetic (AF) ordering through neutron diffraction. A negative thermal expansion phenomenon is observed below TN2, which has been interpreted as a result of competing normal thermal contraction and long-range AF spin ordering through counterbalanced WO4 and NiO6 polyhedral local distortion. The AF spin structure has been modeled and used to show that Ni spins with a saturated magnetic moment of ∼1.90(27)μB that lies in the a−c plane approximately 46∘(±10∘) off the a axis. The experimental results are compared and found to be consistent with theoretical calculations using density-functional theory with a generalized gradient approximation plus on-site Coulomb interaction. ©2015 American Physical Society
ISSN: 2469-9969
Appears in Collections:Journal Articles

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