Exploring high temperature magnetic order in CeTi_1-xSc_xGe

Abstract

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]

Itinerant to local transformation and critical point in Ni-rich Ce2(Ni1-yPdy)2Sn alloys

“…4a, that should end in a critical point because of an entropy bottleneck [11]. This type of behavior was also observed in URu 2 Si 2 under magnetic field [18] and CeTi y Sc 1−y Ge [19]. The latter shows a very similar divergency of its C m /T maximum also approaching a structural instability.…”

Minimal model for the magnetic phase diagram of CeTi1-xScxGe, Oropesa1, Encina2, Pedrazzini3 et al. 2020Journal of Magnetism and Magnetic Materials1000View full textAdd to dashboardCite

“…izes in the CeFeSi-type structure and does not present a magnetically ordered state at low temperatures. In recent works, Sereni et al studied the evolution of the thermodynamic and transport properties of CeTi 1−x Sc x Ge for samples with 0.25 x ≤ 1[4,5,6]. A continuous reduction of T N with decreasing Sc content was observed for x down to ∼ 0.5 and ferromagnetic behavior for lower values of x down to ∼ 0.25 where there is a change in the crystal structure to CeFeSi-type with no magnetic order.The interest in the RTX family has also been fueled by the large magnetocaloric effect (MCE) in the R=Gd compounds.…”