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Butterfly hysteresis loop at non-zero bias field in antiferromagnetic molecular rings: cooling by adiabatic magnetization

O. Waldmann·R. Koch·S. Schromm·P. Müller·I. Bernt·R. W. Saalfrank
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Abstract

At low temperatures, the magnetization of the molecular ferric wheel NaFe$_6$ exhibits a step at a critical field $B_c$ due to a field-induced level-crossing. By means of high-field torque magnetometry we observed a hysteretic behavior at the level-crossing with a characteristic butterfly shape which is analyzed in terms of a dissipative two-level model. Several unusual features were found. The non-zero bias field of the level-crossing suggests the possibility of cooling by adiabatic magnetization.

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O. Waldmann, R. Koch, S. Schromm, P. Müller, I. Bernt, R. W. Saalfrank. 2002-10-14. Butterfly hysteresis loop at non-zero bias field in antiferromagnetic molecular rings: cooling by adiabatic magnetization. https://doi.org/10.1103/physrevlett.89.246401

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