التفاصيل البيبلوغرافية
| العنوان: |
Spin Ice: a Laboratory for Low Temperature Physics. |
| المؤلفون: |
Bramwell, S. T.1, Fennell, T.2 |
| المصدر: |
AIP Conference Proceedings. 2006, Vol. 850 Issue 1, p1101-1108. 8p. 5 Diagrams, 4 Graphs. |
| مصطلحات موضوعية: |
*ICE crystals, *HYDROGEN analysis, *ENTROPY, *FERROMAGNETIC materials, *MAGNETIC fields, *LOW temperatures |
| مستخلص: |
Pauling’s model of hydrogen disorder in water ice illustrates how zero point entropy can occur in a practical system. ‘Spin Ice’ is a precise analogue of Pauling’s model in which hydrogen displacement vectors are replaced by Ising spins and the ‘ice rules’ are enforced by ferromagnetic coupling. The model is approximated almost ideally by several rare earth pyrochlore magnets of general formula R2M2O7 (R = Ho, Dy, M = Ti, Sn). These materials have a disordered low temperature magnetic state with macroscopic degeneracy and zero point entropy. In this selective review we will describe the experimental physics of spin ice and focus on two particular topics. The first is how one can manipulate the very large ground state degeneracy — removing it completely, removing it partially or even increasing it — by the application of magnetic fields to single crystal samples. The second topic is a consideration of the question: while we clearly have a good phenomenolgical understanding of the spin ice materials, do we have an adequate microscopic understanding of their properties? Attempts to answer this question have revealed some interesting new physics, but at a practical level the answer is still ‘not yet’. We hope that this discussion will inspire some future experiments in the low temperature regime. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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