Magnetic and hysteretic properties of Fe-filled nanotubes

The hysteretic properties of Fe-filled carbon nanotubes samples are present ed and related to their magnetic phase distribution obtained by Mossbauer s pectroscopy. The most relevant result corresponds to the observation of a h igh anisotropy gamma -Fe phase, getting magnetically ordered at 100 K. Belo w this temperature, irreversibility in the high field zero field cooling (Z FC)-field cooling (FC) curves, as well as shifted hysteresis loops are obse rved. These results are explained in terms of the blocking of the high anis otropy phase and the development of exchange anisotropy.