Raman Investigations of C-, Li- and Mn-Doped MgB2 |
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Authors: | P Parisiades E Liarokapis N D Zhigadlo S Katrych J Karpinski |
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Affiliation: | (1) Department of Physics, National Technical University of Athens, Athens, 15780, Greece;(2) Solid State Physics Laboratory, ETH, Zurich, Switzerland |
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Abstract: | A systematic micro-Raman study of the atomic substitution effects has been carried out on single crystals of MgB2, including C-doping for B and Li- or Mn-doping for Mg. The spectra of C (electron)-doped compounds exhibit remarkable differentiations
with respect to pure MgB2, and new bands of E2g and A1g/B1g symmetry play the dominant role in the substituted spectra. We have observed a two-mode behavior apparently driven by the
electron–phonon coupling strength and associated with an electronic topological transition of the σ bands. On the other hand, Li (hole) and Mn (magnetic impurity) doping do not seem to affect the well-defined broad band at
600 cm−1. Combining Raman investigations and T
c
-interdependence shows that this band is not related with the transition temperature, questioning its relationship to superconductivity
in diborides.
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Keywords: | Superconductivity MgB2 Raman spectroscopy |
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