Crystal, magnetic, calorimetric and electronic structure investigation of GdScGe1–xSbx compounds. (9th November 2017)

• Record Type: Journal Article
• Authors: Guillou, F; Pathak, A K; Hackett, T A; Paudyal, D; Mudryk, Y; Pecharsky, V K
• Is Part Of: Journal of physics. Volume 29:Number 48(2017)
• Publication Date: 2017-11-09
• Subjects: rare-earth compounds -- magnetic properties -- gadolinium intermetallics -- magnetic transition; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa93aa
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Experimental investigations of crystal structure, magnetism and heat capacity of compounds in the pseudoternary GdScGe-GdScSb system combined with density functional theory projections have been employed to clarify the interplay between the crystal structure and magnetism in this series of RTX materials ( R = rare-earth, T = transition metal and X = p-block element). We demonstrate that the CeScSi-type structure adopted by GdScGe and CeFeSi-type structure adopted by GdScSb coexist over a limited range of compositions 0.65 ⩽ x ⩽ 0.9 . Antimony for Ge substitutions in GdScGe result in an anisotropic expansion of the unit cell of the parent that is most pronounced along the c axis. We believe that such expansion acts as the driving force for the instability of the double layer CeScSi-type structure of the parent germanide. Extensive, yet limited Sb substitutions 0 ⩽ x < 0.65 lead to a strong reduction of the Curie temperature compared to the GdScGe parent, but without affecting the saturation magnetization. With a further increase in Sb content, the first compositions showing the presence of the CeFeSi-type structure of the antimonide, x ≈ 0.7, coincide with the appearance of an antiferromagnetic phase. The application of a finite magnetic field reveals a jump in magnetization toward a fully saturated ferromagnetic state. This antiferro–ferromagnetic transformation is not associated with a sizeable latent heat, as confirmed by heat capacity measurements. The electronic structure calculations for x = 0.75 indicate that the key factor in the conversion from the ferromagnetic CeScSi-type to the antiferromagnetic CeFeSi-type structure is the disappearance of the induced magnetic moments on Sc. For the parent antimonide, heat capacity measurements indicate an additional transition below the main antiferromagnetic transition.