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- Title
Magnetic phase transition for defect induced electron spins from fully metal-semiconductor separated SWCNTs.
- Authors
Havlicek, M.; Chernov, A.; Jantsch, W.; Wilamowski, Z.; Yanagi, K.; Kataura, H.; Rümmeli, M. H.; Malissa, H.; Kuzmany, H.
- Abstract
ESR experiments from PtRhRe grown and highly semiconductor-metal separated single-walled carbon nanotubes (SWCNTs) were performed at 9.45 GHz and temperatures T between 0.39 and 200 K. No explicit evidence was found for a response from itinerant electrons in the metallic tubes. Rather, in both the metallic (M) and the semiconducting (SC) tubes, the ESR signal originates from quasi-localized defect spins but interactions with free electrons render the two systems characteristically different. The spin susceptibility was of Curie-Weiss type for T ≥ 10 K. For annealed samples it drops for lower T indicating a transition to a ferromagnetic state. Linewidths decrease and increase with increasing T for M and SC tubes, respectively. As a consequence they cross for the two systems. Interaction of spins with free carriers in M tubes via an RKKY type mechanism and increase of linewidth with temperature for SC tubes due to spin-lattice interaction is suggested to be responsible for this.
- Publication
Physica Status Solidi (B), 2012, Vol 249, Issue 12, p2562
- ISSN
0370-1972
- Publication type
Article
- DOI
10.1002/pssb.201200426