Structural and magnetic properties of Nd2Fe17−δGaδ (δ⩽2)
| Autor: | Kannan M. Krishnan, Ian P. Swainson, Gareth Thomas, Z. Altounian, Er. Girt, M. Guillot |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 87:5323-5325 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.373335 |
| Popis: | Magnetization measurements of Nd2Fe17−δGaδ (δ=0–2) show that the saturation magnetization, Ms, decreases with an increase in Ga content from 40.4 μB/f.u. for Nd2Fe17 to 36.1 μB/f.u. for Nd2Fe15Ga2 at 4.2 K. Neutron diffraction data at 25 K show that the magnetic moment of Fe depends on its crystallographic site and decreases in the order Fe(6c)>Fe(18f)⩾Fe(18h)⩾Fe(9d). The magnetic moments of Fe(9d), Fe(18f), and Fe(18h) are found to be practically independent of the Ga content. However, the magnetic moment of Fe(6c) decreases from 2.81(9) μB in Nd2Fe17 to 2.14(9) μB in Nd2Fe15Ga2. The decrease of the Fe(6c) moment clearly reduces the exchange interaction between Fe(6c)–Fe(6c) dumbbell pairs which explains the decrease in the anomalous thermal expansion with an increase in Ga concentration. The reduced Fe(6c)–Fe(6c) exchange interaction may also play an important role in increasing the Curie temperature, TC, with Ga content; TC increases from 327 K in Nd2Fe17 to 535 K in Nd2Fe15Ga2. |
| Databáze: | OpenAIRE |
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