Properties near magnetic instability of heavy-electron compounds Ce₃M₄Sn₁₃ and La₃M₄Sn₁₃, with M=Co, Rh and Ru

Abstract

In this review, we report the thermodynamic, magnetic and electronic transport properties of the skutterudite-related Ce₃M₄Sn₁₃ and La₃M₄Sn₁₃ intermetallic compounds with M = Co, Rh and Ru, which display a variety of behaviours. Ce₃M₄Sn₁₃ exhibit a large increase in C/T with a maximum value of about 4 JK^-2mol^-1_Ce due to strong electron and short-range magnetic correlations. These compounds show a crossover from a magnetically correlated heavy-fermion state to a single impurity state in applied magnetic fields. In order to study the proximity of Ce₃Co₄Sn₁₃ to the possible magnetic quantum critical point (QCP), we investigated the system of Ce_3-xLa_xCo₄Sn₁₃ alloys. We found the critical concentration , which separates the magnetically correlated state () from a single impurity state (), however the low-T C(T)/T and the magnetic susceptibility behaviours are not characteristic of the QCP. With increasing of the magnetic field, resistivity follows power law behaviour for the samples , with n strongly field dependent. The -anomaly is discussed on the base of spin-fluctuation theory of Moriya and Takimoto. Specific heat data show that La₃M₄Sn₁₃ are typical BCS superconductors, however, La₃Rh₄Sn₁₃ and La₃Ru₄Sn₁₃ exhibit a second superconducting phase, characteristic of inhomogeneous superconductors.

Keywords:

• rare earth compounds
• strongly correlated electron systems
• Kondo effect
• superconductivity

Acknowledgements

We thank National Science Centre (NCN) for financial support, on the basis of decision No. DEC-2012/07/B/ST3/03027.