Lattice effects in diborides

Parisiades, P; Liarokapis, E

dc.contributor.author	Parisiades, P	en
dc.contributor.author	Liarokapis, E	en
dc.date.accessioned	2014-03-01T01:35:55Z
dc.date.available	2014-03-01T01:35:55Z
dc.date.issued	2011	en
dc.identifier.issn	1557-1939	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21250
dc.subject	Diborides	en
dc.subject	Electron-phonon coupling	en
dc.subject	Phase separation	en
dc.subject	Raman spectroscopy	en
dc.subject	Superconductivity	en
dc.subject.classification	Physics, Applied	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	Atomic substitutions	en
dc.subject.other	Diborides	en
dc.subject.other	Doping dependence	en
dc.subject.other	Electron phonon couplings	en
dc.subject.other	Electron-doping	en
dc.subject.other	Electronic transition	en
dc.subject.other	Hard modes	en
dc.subject.other	Internal strains	en
dc.subject.other	Lattice effect	en
dc.subject.other	Li substitution	en
dc.subject.other	Magnetic pair breaking	en
dc.subject.other	Mn ions	en
dc.subject.other	Phase co-existence	en
dc.subject.other	Phase competition	en
dc.subject.other	Phonon frequencies	en
dc.subject.other	Two-mode behavior	en
dc.subject.other	Atomic spectroscopy	en
dc.subject.other	Fermi surface	en
dc.subject.other	Manganese	en
dc.subject.other	Phase separation	en
dc.subject.other	Phonons	en
dc.subject.other	Raman scattering	en
dc.subject.other	Raman spectroscopy	en
dc.subject.other	Superconductivity	en
dc.subject.other	Borides	en
dc.title	Lattice effects in diborides	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s10948-010-0898-2	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s10948-010-0898-2	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	The lattice effects in diborides have been investigated by Raman spectroscopy using several atomic substitutions for Mg and B. The doping dependence of T (c) can be associated with the gradual filling of the sigma- and the pi-bands and the modifications in the Fermi surface. The data show that C doping for B induces a much faster reduction in T (c) than Al for Mg, while the simple Li substitution has a minor effect. On the other hand, the double Li-C substitution reduces T (c) faster than the simple C doping, which can be attributed to the different role of hole and electron doping for the pi- and sigma-bands. Finally, Mn ions have a drastic effect on superconductivity apparently acting as magnetic pair breaking centers. In the Raman spectra of the mixed compounds, two modes of E-2g symmetry appear at similar to 600 cm(-1) and similar to 850 cm(-1) (defined as the soft and hard modes, respectively), which do not evolve one to the other with doping, but they coexist in a typical two-mode behavior for both Mg(B1-x C (x) )(2) and Mg1-x Al (x) B-2 sets of compounds. MgB2 appears to be metastable with intrinsic structural and electronic phase competition, close to topological electronic transitions of the Fermi surface that can be tuned by doping or internal strain from the atomic substitutions. The analysis of the phonon frequency dependence on doping indicates that the behavior of the renormalized mode cannot explain the reduction of T (c) in the phase coexistence level. It appears that other effects play also an important role in the superconductivity of diborides.	en
heal.publisher	SPRINGER	en
heal.journalName	Journal of Superconductivity and Novel Magnetism	en
dc.identifier.doi	10.1007/s10948-010-0898-2	en
dc.identifier.isi	ISI:000289855700008	en
dc.identifier.volume	24	en
dc.identifier.issue	1-2	en
dc.identifier.spage	49	en
dc.identifier.epage	56	en