Superconductivity in filled skutterudite LaxRh4P12 (0.5 < x ≤ 1): Experimental and computational studies. (March 2019)

• Record Type: Journal Article
• Authors: Imai, Motoharu; Arai, Masao; Taniguchi, Takashi
• Is Part Of: Acta materialia. Volume 166(2019)
• Page Start: 543
• Page End: 550
• Publication Date: 2019-03
• Subjects: Superconductivity -- Intermetallic compounds -- Electrical resistivity/conductivity -- Ab initio calculations -- Filled skutterudite; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.01.002
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The superconductivity in filled skutterudites La x Rh4 P12 (0.5 &lt; x ≤ 1) was investigated by experiments and first-principles calculations. La x Rh4 P12 species with varying La contents ( x ) were synthesized at high pressures and high temperatures. Increasing the synthesis pressure resulted in an increase in x . Moreover, T C was found to increase with increasing values of x . The highest value of T C was found to be 16.4 K for x = 0.99 (3). Electronic structure calculations for RhP3 and LaRh4 P12 showed that filling of La into RhP3 significantly increased the density of states (DOS) at the Fermi energy E F, N ( E F ). This was attributed to the fact that an increase in the number of valence electrons due to La filling shifts the E F to higher energies, at which the DOS has a moderate value. Phonon calculations showed that the filling of La atoms into RhP3 leads to a La phonon band and modification of RhP phonon bands in the relatively low-energy region. The increase in N ( E F ) and modification of phonon spectra caused by La filling enhances the electron–phonon coupling constant, leading to superconductivity in LaRh4 P12. The T C value calculated assuming the Bardeen–Cooper–Schrieffer mechanism was consistent with the experimentally observed T C . A comparison between LaRh4 P12 and a conventional filled skutterudite showed that the former is an intercalation-type compound, the antibonding states of which are important for its transport properties, while the latter is a Zintl-phase-type compound, for which the bonding states are important. Graphical abstract: Image 1