The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with TN = 47 K, but its local or itinerant nature was not deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport and thermal properties of CeTi1−xScxGe alloys within the range of stability of the CeScSi-type structure: 0.25 ≤ x ≤ 1. Along this concentration range, this strongly anisotropic system presents a complex magnetic phase diagram with a continuous modification of its magnetic behavior, from ferromagnetism (FM) for 0.25 ≤ x ≤ 0.50 (with 7 K≤ TC ≤ 16 K) to AFM for 0.60 ≤ x ≤ 1 (with 19 K≤ TN ≤ 47 K). The onset of the AFM phase is associated to a metamagnetic transition with a critical field increasing from Hcr = 0 at x ≈ 0.55 to ≈ 6 Tesla at x = 1, coincident with an increasing contribution of the first excited crystal electric field doublet. At a critical point xcr = 0.65 a second transition appears at TL ≤ TN . In contrast to observations in itinerant systems like CeRh2Si2 or CeRh3B2, no evidences for significant hybridization of the 4f electrons at large Sc contents were found. Therefore, the exceptionally large TN of CeScGe can be attributed to an increasing RKKY inter-layer interaction as Sc content grows.

Se presenta un estudio del poder termoeléctrico, S(T), a bajas temperaturas de la aleación Ce(Pd 1-x Cu x) 2 Si 2. Las curvas de S(T) tienen una dependencia similar en todo el rango de sustitución, con tres anomalías: un máximo positivo de alta temperatura, un mínimo negativo y un máximo de bajas temperaturas. Se discute brevemente el origen de las anomalías, para lo cual se compara S(T) con datos de resistividad eléctrica provenientes de la literatura. Para realizar las mediciones de poder termoeléctrico se diseñó y construyó un dispositivo que puede ser montado en diversos crióstatos.

Most of magnetic transitions related to Ce ordering are found below T ord ≈ 12K. Among the few cases exceeding that temperature, two types of behaviors can be distinguished. One of them is related to the rare cases of Ce binary compounds formed in BCC structures, with a quartet ground state, whose degeneracy (N = 4) is reduced by undergoing different types of transitions mostly connected with structural modifications. The other group shows evidences of itinerant character with the outstanding example of CeRh3B2 showing the highest ordering temperatures T ord = 115K. The second highest ordering temperature has been reported for CeScGe with T ord = 47K, but the nature of this magnetic state has not been investigated very deeply. In order to shed more light into this unusual high temperature ordering we studied the structural, magnetic, transport and thermal properties of CeTi1−xScxGe alloys in the stability range of the CeScSi-type structure 0.25 ≤ x ≤ 1 This system presents a rich variety of magnetic behaviors along this concentration range, with the magnetic ordering growing from ferromagnetic (FM) TC ≈ 7K up to an antiferromagnetic (AFM) transition at TN = 47K. The different regions show the following characteristics: i) on the Ti rich side (0.25 ≤ x ≤ 0.50) it exhibits a FM ground state (GS) with large saturation magnetization values Msat up to ≈ 1.15µB. ii) Around x = 0.60, the first crystal electric field excited doublet starts to contribute to the GS magnetic properties. Furthermore an AFM component with a connected metamagnetic transition appears. iii) At x = 0.65 a clear change in the GS nature is associated to a critical point above which the GS properties can be described like for an itinerant system (with decreasing Msat) and an effective GS degeneracy N ef f = 4. iv) For x > 0.65, the magnetic phase boundary splits into two transitions, with an intermediate phase presenting incommensurate spin density waves features. arXiv:1403.4490v1 [cond-mat.str-el]