Superconductivity and structural variation of the electron-correlated layer systems Sr(Pd1-xTx)(2)Ge-2 (T = Co, Ni, Rh; 0 <= x <= 1)

dc.contributor.author	Wang, J. W.
dc.contributor.author	Chen, I. A.
dc.contributor.author	Hung, T. L.
dc.contributor.author	You, Y. B.
dc.contributor.author	Ku, H. C.
dc.contributor.author	Hsu, Y. Y.
dc.contributor.author	Ho, J. C.
dc.contributor.author	Chen, Y. Y.
dc.date.accessioned	2012-06-18T20:05:55Z
dc.date.available	2012-06-18T20:05:55Z
dc.date.issued	2012-01-31
dc.identifier.citation	Wang J.W., Chen I.A., Hung T.L., You Y.B., Ku H.C., et al. 2012. "Superconductivity and structural variation of the electron-correlated layer systems Sr(Pd1-xTx)(2)Ge-2 (T = Co, Ni, Rh; 0 <= x <= 1)". Physical Review B - Condensed Matter and Materials Physics. 85 (2).	en_US
dc.identifier.issn	1098-0121
dc.identifier.issn	1550-235X
dc.identifier.uri	http://hdl.handle.net/10057/5142
dc.identifier.uri	http://dx.doi.org/10.1103/PhysRevB.85.024538
dc.description	Click on the DOI link below to access the article (may not be free).	en_US
dc.description.abstract	Superconductivity variations deduced from the x-ray diffraction and the magnetic and heat-capacity measurements in the pseudoternary Sr(Pd1-xTx)(2)Ge-2 layer system [Pd(4d(8)), T = Co(3d(7)), Ni(3d(8)), or Rh(4d(7)); 0 <= x <= 1] are reported. For the BaFe2As2-type tetragonal structure, the degenerate nd(7) or nd(8) orbitals of transitionmetal T are split by c-axis squeezed TGe4 tetrahedral crystal field in the T-Ge layer. For the isoelectronic Sr(Pd1-xNix)(2)Ge-2 system, the superconducting transition temperature T-c decreases monotonically from 3.12 K for 4d-band SrPd2Ge2 to 0.92 K for 3d-band SrNi2Ge2, where major contributions of conduction electrons are from the half filled dispersive three-dimensional (3D)-like upper-lying nd(xz,yz) bands. For the Sr(Pd1-xRhx)(2)Ge-2 system, T-c decreases to 2.40 K with 25% of 4d(7) Rh substitution. For the Sr(Pd1-xCox)(2)Ge-2 system, T-c decreases sharply to 2.58 K with only 3% of 3d(7) Co substitution. No superconductivity is e! xpected for SrRh2Ge2 and SrCo2Ge2 with lower density of states in d(xz,yz) bands due to down shift of Fermi energy E-F by one less electron per transition metal. The lower T-c of the present electron-overdoped (nd(7) or nd(8)) compound is due to dispersive 3D-like nd(xz,yz) conduction bands with weak electron correlation, in comparison with the less-electron-doped (3d(6.1)) 22-K superconductor BaFe1.8Co0.2As2 or the hole-doped (3d(5.9)) 38-K superconductor Ba0.6K0.4Fe2As2 where electron contribution is from less dispersive 2D-like lower-lying 3d(xy) conduction band with stronger electron correlation.	en_US
dc.language.iso	en_US	en_US
dc.publisher	American Physical Society	en_US
dc.relation.ispartofseries	Physical Review B - Condensed Matter and Materials Physics;2012:, v.85, no.2
dc.subject	Superconducting materials	en_US
dc.subject	X-ray diffraction	en_US
dc.subject	Inorganic compounds	en_US
dc.subject	Effects of crystal defects	en_US
dc.subject	Doping and substitution	en_US
dc.title	Superconductivity and structural variation of the electron-correlated layer systems Sr(Pd1-xTx)(2)Ge-2 (T = Co, Ni, Rh; 0 <= x <= 1)	en_US
dc.type	Article	en_US
dc.description.version	Peer reviewed
dc.rights.holder	© 2012 American Physical Society