Low temperature electrical resistivity and thermopower in CeSc1-yTiyGe

S. ENCINA; F. MANGUSSI; P. PEDRAZZINI; M. GÓMEZ BERISSO; N. CAROCA-CANALES; C. GEIBEL; J.G. SERENI

S.C. de Bariloche

Conferencia; Advanced Topics of Magnetism and Superconductivity (AToMS-2014); 2014

Centro Atomico Bariloche (CNEA) e Instituto Balseiro (CNEA-UNCuyo)

CeScGe shows antiferromagnetic order at TMO = 47 K, the second highest ordering temperatures among Ce-based intermetallic systems. CeTiGe, on the other hand, is a non-magnetic heavy fermion compound in which low temperature magnetism can be induced through a metamagnetic transition occuring roughly at 120 kOe. These compounds crystallize in two related tetragonal structures, CeScSi and CeFeSi-type respectively. The study of the resulting alloy, CeSc1-y TiyGe, could shed light on the conditions that lead to such anomalous magnetic ground states.In this contribution we will present electrical resistivity, r(T ), and thermopower (Seebeck effect, S(T )) measurements on a series of alloys covering the whole substitution range. These measurements complement the information available on thermal properties measured in this system [1]. On the Sc-rich side (CeScSi-type structure) we use the resistivity data to trace the suppression of TMO(y) as Ti-content increases. The r(T ) anomaly at TMO(y) changes from a kink at y = 0, to a superzone or SDW-like resistivity increase for 0.05 <= y <= 0.35 and back to a kink for y > 0.4. This kink is observed up to y ≥ 0.23, i.e. close to the stability limit of the CeScSi-structure. We use this information, together with low-field magnetization data, to infer that a change in the nature of the TMO(y) transition occurs. The proposedscheme is consistent with high-field resistivity measurements on selected samples (up to 160 kOe). The thermopower S(y, T ) increases with Ti-doping, displaying a double-maxima or single-maximum structure depending on y. This evolution is typical of Ce-compounds and alloys that progressively loose their magnetism. Contrary to what is observed in the r(T ) data, the magnetic anomaly at TMO (y) manifests in S(T ) as a very small kink. To understand this apparent inconsistency we propose that more than one band contributes tothe electronic transport. The proper detection of small features in S(T ) is only possible with a newly implemented ac-detection technique for the thermopower. This technique relies on low noise preamplification of two thermocouple signals measured with a lock-in technique.[1] J.G. Sereni et al., arXiv:1403.4490 (2014).