Critical thermodynamics of dysprosium ethyl sulphate, a pure dipolar Ising ferromagnet |
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Authors: | R Frowein and J K?tzler |
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Abstract: | Using a SQUID magnetometer the magnetization of the Ising ferromagnet dysprosium ethyl sulphate has been measured in the temperature range 0.015–3K and in external fields 0.004–30 Oe. The results atT 0.4 K (precritical regime) confirm the pure dipolar nature of the magnetic interactions. Particular interest has been paid to the immediate neighbourhood of the critical pointT
c
=118.17 mK andH=0 where the zero-field susceptibility (T) aboveT
c
, the spontaneous magnetizationM
s
(T), and the magnetization atT
c
,M
c
(H), can be described by mean field laws modified by logarithmic singularities. The critical amplitudes , B, andD of , M
s
andM
c
, respectively, satisfy the relation (2/3![Gamma](/content/T36435P0JJH28343/xxlarge915.gif) B
2)1/3=D. All these results agree with predictions of (i) the Larkin-Khmel'nitskii theory and (ii) exact solutions of the renormalization group equations for 3-dimensional dipolar Ising ferromagnets. |
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Keywords: | |
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