Local character of the highest antiferromagnetic temperature of Ce systems in Sc-rich CeTi1-xScxGe

Abstract

The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with TN=47 K , but its local or itinerant nature has not been 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 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 T 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 4 f electrons at large Sc contents were found. Therefore, the exceptionally large TN of CeScGe can be attributed to an increasing Ruderman-Kittel-Kasuya-Yosida interaction between Ce double layers as Sc content grows.