Superconductivity of LaRu4X12 (X = P, As and Sb) with skutterudite structure

Citation
T. Uchiumi et al., Superconductivity of LaRu4X12 (X = P, As and Sb) with skutterudite structure, J PHYS CH S, 60(5), 1999, pp. 689-695
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
ISSN journal
0022-3697 → ACNP
Volume
60
Issue
5
Year of publication
1999
Pages
689 - 695
Database
ISI
SICI code
0022-3697(199905)60:5<689:SOL(=P>2.0.ZU;2-7
Abstract
Ternary ruthenium pnictides with a skutterudite structure, LaRu4X12(X = P, As and Sb) and La1-xCexRu4P12(x = 0.05, 0.1 and 0.2) were prepared at high temperatures and pressures. The electrical resistivity and the de magnetic susceptibility of these compounds and alloys were measured at low temperatu res. Superconducting transition temperatures (T(c)s) in LaRu4X12(X = P, As and Sb) were 7.2, 10.3 and 2.8 K, respectively. The specific heat of LaRu4P 12 was measured between 2 and 20 K. The specific-heat data can be fit to th e expression C-n = gamma T + beta T-3, where gamma = 26.0 mJ/mol K-2 and P = 0.372 mJ/mol K-4, resulting in a Debye temperature (Theta(D)) = 446 K. Th e electronic density of the states at the Fermi energy for LaRu4P12 was 0.4 2 state/eV-atom. This value was considerably smaller than that of LaRu4As12 . The resistivity of La1-xCexRu4P12 (x = 0, 0.05, and 0.1) rapidly decrease s with decreasing temperature, and suddenly falls between 5 and 7 K. The T- c of the alloys decreases with increasing x. The de susceptibility of the a lloys sharply decreases at around the T(c)s. The decrease of T-c and diamag netic susceptibility with increasing x arises from an f-electron in the tri valent Ce ion. The resistances of LaRu4X12 (X = P, As and Sb) were measured as a function of the applied magnetic field at constant temperatures betwe en 0.4 and 8 K. The upper critical fields H(c2)s Of LaRu4X12 (X = P, As and Sb) are 3.65, 0.72 and 0.46 T (tesla) at 0 K, respectively. In this articl e, superconducting properties of LaRu4X12 (X = P, As and Sb) are discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.