Filled Skutterudites: Magnetic and Electrical Transport Properties

Multigap superconductivity in the filled-skutterudite compound LaRu4As12 probed by muon spin rotation

“…The muon gyromagnetic ratio is γ μ /2π = 135.53 MHz/T; σ is the Gaussian muon spin relaxation rate, and is the initial phase of the signal at the detectors. The values of A 0 = 0.66 (1) and A bg = 0.34(1) were estimated by fitting 0.31 K data, and were kept fixed during the analysis of other temperature data.…”

“…Materials scientists and physicists have been intrigued by properties of the ternary transition metal pnictides (Pn) with the chemical formula MT 4 Pn 12 (M = alkali metal, alkalineearth metal, lanthanide, or light actinide element; T = Fe, Ru, or Os; Pn = P, As, or Sb), which crystallize in the filled skutterudite structure with space group Im 3 (No. 204) [1]. Examples include excellent thermoelectric performance [2,3] and strongly correlated electron phenomena such as unconventional superconductivity [4][5][6], quadrupolar ordering [7][8][9][10][11], non-Fermi-liquid behavior [12], hybridization gap or Kondo phenomena [12][13][14][15][16][17], and unusual metal-insulator transitions [18].…”

“…This enhancement is even more intriguing if one takes into account that LaRu 4 As 12 does not show any distinct differences in both the conduction electron density of states at the Fermi level and the vibrational properties [36,37]. Another remarkable feature of LaRu 4 As 12 is that it has several arguments for multiband superconductivity [1][2][3][4][5]33,36]. Specifically, the temperature dependence of the lower critical field H c1 displays a sharp anomaly deep in the superconducting state, indicative of a rarely observed case of almost decoupled bands [33].…”

Superconducting Gap Structure of Filled Skutterudite LaOs4As12 Compound through μSR Investigations

“…Due to their potential as thermoelectric materials for either refrigeration or power generation applications, many filled skutterudite compounds with RT 4 X 12 stoichiometry (R = alkali metals, alkaline earth metals, lanthanides, or light actinides; T = Fe, Os, Ru; X = P, As, Sb) have lately been the focus of several investigations [1][2][3]. With two formula units RT 4 X 12 per unit cell, these compounds form a body-centered cubic structure (space group Im 3, No: 204).…”

“…The unique band structure of these compounds and the hybridization effects between localized f electrons and conduction electrons appear to play a crucial role, in addition to the fact that the origin of the majority of those unconventional phenomenologies is unknown. It was recently revealed that the Fermi level of La compounds is placed at a prominent peak arising from the T-d band manifold, which might contribute to electronic instability [1,17]. Several La-based compounds LaT 4 X 12 are especially remarkable within the filled skutterudite class due to their remarkable superconducting properties.…”