Publication Date

5-2-2021

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Physics and Astronomy, Ames Laboratory

OSTI ID+

1784535

Report Number

IS-J 10485

DOI

10.1016/j.jmmm.2021.168062

Journal Title

Journal of Magnetism and Magnetic Materials

Volume Number

535

First Page

168062

Abstract

A recently-developed molecular field theory (MFT) has been used to fit single-crystal magnetic susceptibility χ versus temperature T data below the respective antiferromagnetic ordering temperature T N for a variety of collinear and coplanar noncollinear Heisenberg antiferromagnets. The spins in the system are assumed to interact by Heisenberg exchange and to be identical and crystallographically equivalent. The fitting parameters for χ(T ) of collinear antiferromagnets are measurable quantities: the Weiss temperature θ p in the Curie-Weiss law, TN, χ(T N), and the spin S. For coplanar noncollinear helix and cycloid structures, an additional fitting parameter is the turn angle between layers of ferromagnetically-aligned spins. Here MFT fits to anisotropic χ(T) data from the literature for single crystals of the collinear antiferromagnets GdCu 2Si 2 and CuO and the noncollinear antiferromagnets LiCrO 2 with a 120° cycloidal structure and α-CaCr 2O 4 with a 120° helical structure below their respective N´eel temperatures are presented. The MFT fit to the anisotropic χ(T ≤ T N) data for CuO is poor, whereas the fits to the data for GdCu 2Si 2, LiCrO 2, and α-CaCr 2O 4 are quite good. The poor fit for CuO is attributed to the influence of strong quantum fluctuations associated with the small Cu spin and the quasi-one-dimensional magnetism that are not taken into account by the MFT. The magnetic contribution to the zero-field heat capacity of the collinear antiferromagnet GdNiGe 3 at T ≤ T N is also fitted by the MFT.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Monday, May 02, 2022

Included in

Metallurgy Commons

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