M. Havlicek, W. Jantsch, Z. Wilamowski, K. Yanagi, H. Kataura, M. H. Rummeli, H. Malissa, A. Tyryshkin, S. Lyon, A. Chernov, H. Kuzmany
The ESR response from highly metal-semiconductor(M-SC) separated SWCNTs for temperatures T between 0.39 and 200 K is characteristically different for the two systems. The signal originates from defect spins but interaction with free electrons leads to a larger line width for M tubes. The latter decreases with increasing T whereas it increases with T for SC tubes. The spins undergo a ferromagnetic phase transition below around 10 K. Indirect exchange is suggested to be responsible for the spin-spin interaction, supported by RKKY interaction in the case of M tubes. For SC tubes spin-lattice relaxation via an Orbach process is suggested to determine the line width.
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http://arxiv.org/abs/1206.4543
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