ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Zero-field ac susceptibility and isothermal magnetization of the quasi-2D alkanediammonium copper tetrahalide series, [NH3(CH2)nNH3]CuX4, where n=4, 5, 6, and 10 with X=Cl and Br, are reported. The 3D antiferromagnetic ordering temperature Tc for the Cl compounds is determined. It is shown that the critical susceptibilities decay exponentially as the temperature increases (T(approximately-greater-than)Tc). A power-law divergence at Tc is seen in the Br compounds with n=7 and 10. This behavior is characteristic of 3D ferromagnetic ordering at Tc. The critical exponent γ for the initial susceptibility (T(approximately-greater-than)Tc) has been obtained for the Br compounds. It is found that there is a second (minor) peak below Tc in the Br compounds with n=5 and 7. The transition associated with this peak may be interpreted as a long range (spontaneous) ordering due to very small spin anisotropies, such as a spin canting between the layers. In the Br compounds the isothermal magnetization is suppressed in low fields, and the value of the critical exponent δ estimated from the isothermal data is considerably smaller than that given by standard models. Spatial- and spin-dimensionality crossovers are apparent in the both initial susceptibility and isothermal magnetization data.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.353635
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