Double-phase transition and giant positive magnetoresistance in the quasi-skutterudite Gd3Ir4Sn13

Abstract

The magnetic, thermodynamic and electrical/thermal transport properties of the caged-structure quasi-skutterudite Gd 3 Ir 4 Sn 13 are re-investigated. The magnetization M (T ), specific heat C p (T ) and the resistivity ρ(T ) reveal a double-phase transition -at T N 1 ∼ 10 K and at T N 2 ∼ 8.8 K -which was not observed in the previous report on this compound. The antiferromagnetic transition is also visible in the thermal transport data, thereby suggesting a close connection between the electronic and lattice degrees of freedom in this Sn-based quasi-skutterudite. The temperature dependence of ρ(T ) is analyzed in terms of a power-law for resistivity pertinent to Fermi liquid picture. Giant, positive magnetoresistance (MR) ≈ 80% is observed in Gd 3 Ir 4 Sn 13 at 2 K with the application of 9 T. The giant MR and the double magnetic transition can be attributed to the quasi-cages and layered antiferromagnetic structure of Gd 3 Ir 4 Sn 13 vulnerable to structural distortions and/or dipolar or spin-reorientation effects. The giant value of MR observed in this class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of this work.

Field-Independent Features in the Magnetization and Specific Heat of Sm3Co4Ge13

“…Recent work on R 3 T 4 X 13 [3] reveals the existence of subtle structural distortions in this class of compounds and confirms the findings of earlier reports on Remeika phases [5,7,8,19]. In fact, additional superstructure peaks signifying structural distortions were unraveled in our earlier studies on a Gd-based compound [20]. In that case, the peaks were indexed following the structural distortion with a propagation vector q c = (1/2, 1/2, 0) and the distorted structure was assigned to the space group I4 1 32, similar to the superlattice structure for Gd 3 Rh 4 Sn 13 and La 3 Rh 4 Sn 13 [19].…”

“…The total thermal conductivity, the electronic and phonon contributions are plotted together in Figure 5a. The thermal conductivity of Sm 3 Co 4 Ge 13 closely resembles that of Gd 3 Ir 4 Sn 13 [20]. Novel materials with very low thermal conductivity are of great interest for the design of improved thermoelectric devices.…”

Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13studied through specific heat and inelastic neutron scattering

“…The experimentally measured thermal conductivity κ T (T) of Pr 3 Rh 4 Sn 13 is plotted in figure 7(a) (open squares). The thermal conductivity of Pr 3 Rh 4 Sn 13 follows a linear behaviour in log-scale which is different from the case of Gd 3 Ir 4 Sn 13 [17] or Y 3 Ir 4 Sn 13 [39]. Close to room temperature, the total thermal conductivity of Pr 3 Rh 4 Sn 13 reaches a value of 5 W K −1 m −1 .…”

“…This positional disorder is clearly addressed and described in the case of Ce 3 Rh 4 Sn 13 [15] and Yb 3 Co 4.3 Sn 12.7 [16]. In certain other R 3 T 4 X 13 compounds, a doubling of the unit cell was observed, for example Gd 3 Ir 4 Sn 13 [17,18]. Recently, new members to this class have been discovered through high pressure synthesis-Ca 3 Pt 4+x Ge 13−y and Yb 3 Pt 4 Ge 13 which share the structure type of Pr 3 Rh 4 Sn 13 [19].…”