Superconductivity ofLa3Co4Sn13andLa3Rh4Sn13:

Abstract

We report the electric transport and thermodynamic properties of the skutterudite-related La3Co4Sn13 and La3Rh4Sn13 superconductors. Applying an external pressure to La3Rh4Sn13, the resistive superconducting critical temperature Tc decreases, while the critical temperature of La3Co4Sn13 is enhanced with increasing pressure. The positive pressure coefficient dTc/dP correlates with a subtle structural transition in La3Co4Sn13 and is discussed in the context of lattice instabilities. Specific heat data show that both compounds are typical BCS superconductors. However, La3Rh4Sn13 also exhibits a second superconducting phase at higher temperatures, which is characteristic of inhomogeneous superconductors. We calculate the specific heat for an inhomogeneous superconducting phase, which agrees well with experimental C(T ) data for La3Rh4Sn13. We also found that an applied pressure reduces this second superconducting phase.

Second-order structural transition in the superconductorLa3Co4Sn13

“…In Sr 3 Ir 4 Sn 13 and Sr 3 Rh 4 Sn 13 , the structural transition occurs at T * 147 [3,6] and 138 K [4,7], respectively. In these systems, a pronounced anomaly can be seen at T * in various physical properties [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], including the electrical resistivity, the magnetic susceptibility and the specific heat. With applied pressure or the substitution of Sr by Ca, i.e., (Ca x Sr 1−x ) 3 Ir 4 Sn 13 and (Ca x Sr 1−x ) 3 Rh 4 Sn 13 , T * decreases rapidly, accompanied by a moderate increase in the superconducting transition temperature T c , which peaks near the composition/pressure where T * extrapolates to 0 K. The phase diagrams constructed thus highly resemble the ones constructed for many topical superconductors found in the vicinity of a magnetic quantum critical point [29][30][31][32][33][34].…”

Kondo effect in the quasiskutteruditeYb3Os4Ge13

“…These compounds typically crystalize into the same primitive cubic crystal structure with a space group Pm-3n, but show remarkably different properties depending on the choice of the three elements. For example, in the R 3 T 4 Sn 13 system, compounds with R= La, Sr, Ca, Yb, Th, and T= Ir, Rh are superconductors [6][7][8][9][10][11][12][13][14], whereas those with R= Gd and Eu order magnetically [14,15]. In the R 3 T 4 Ge 13 system, R 3 Ru 4 Ge 13 compounds with R= Nd-Yb show paramagnetic behavior down to 1.5 K, while Lu 3 Ru 4 Ge 13 and Y 3 Ru 4 Ge 13 exhibit diamagnetic and Pauli paramagnetism above 4.2 K, respectively, and become superconducting at lower temperatures [3].…”

Multiband superconductivity in Lu3Os4Ge13

“…These compounds show a variety of unusual magnetic ground states and superconductivity at low temperatures 1 . One such structure with no metalloids was reported by Remeika et al 2 .…”