Crystal, magnetic, calorimetric and electronic structure investigation of GdScGe_1–xSb_xcompounds

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, [Formula: see text] = 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 [Formula: see text]. 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 [Formula: see text] 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, [Formula: see text], 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 [Formula: see text] 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.

Distinctive exchange bias and unusual memory effects in magnetically compensated Pr0.75Gd0.25ScGe

“…Lattice parameters, along with basic magnetic properties, are listed in Table 2. Considering the tetragonal lattice parameters for PrScGe published by Singh et al 29 and GdScGe reported by Guillou et al, 33 and assuming that Vegard's law applies, the expected lattice parameters for Pr 0.75 Gd 0.25 ScGe are a = b = 4.313 Å and c = 15.817 Å. Both are slightly smaller than the experimentally obtained values.…”

“…That being said, it is also possible that the observed minor deviations from the Vegard's law (see above) also affect the RKKY exchange and magnetism. It is worth noting that in this estimate we used the T C = 352 K found in Guillou et al, 33 which is on the higher end of reported T C values for GdScGe: for example, Nikitin et al report 320 K, 18 Manfrinetti et al report 350 K, 36 Couillaud et al report 348 K, 37 and Ivanova et al report 320 K. 34 The two of the lowest T C s of 320 K are likely the result of using commercial grade Gd with much higher concentrations of impurities compared to other reports.…”

“…Guillou et al demonstrated that metamagnetic behaviour emerges when a CeScSi-type (represented by the GdScGe parent) and CeFeSi-type (represented by the GdScSb parent) compounds are combined in a pseudobinary GdScGe 1Àx Sb x by substituting one X-element for another. 33 Further, Ivanova et al reported that by substituting Sc with Ti on the T site and creating the pseudobinary GdSc 1Àx Ti x Ge, one could enhance the already high T C of GdScGe from 320 K for x = 0 to 377 K for x = 1. 34 Adding variable spin-orbit coupling into the mix may lead to additional electronic and magnetic complexities while maintaining crystallographic simplicity, and thus result in remarkable physics when light and heavy lanthanides are combined on the R site.…”

Effect of Electronic Correlations on the Electronic Structure, Magnetic and Optical Properties of the Ternary RCuGe Compounds with R = Tb, Dy, Ho, Er

“…Ternary intermetallic compounds of the RTX series with R = rare-earth metal, T = d metal, X = p element, were studied intensively during the last years, see recent reviews [ 1 , 2 , 3 , 4 ]. A number of interesting magnetic and electric properties of practical and fundamental importance were found in different compounds of the RTX series, including magnetocaloric effect (MCE) [ 5 ] of giant [ 6 , 7 , 8 , 9 , 10 ] and large [ 11 , 12 , 13 ] magnitude and magnetoresistance, an antiferromagnetic to ferromagnetic order transition [ 14 , 15 ] and rich magnetic transition phase diagram [ 16 , 17 , 18 ]. Very recently, another promising application of some RXT was revealed as intermetallic electrides [ 19 , 20 ].…”

Characterization of d and f Electronic States in RSn1.1Ge0.9 (R = Gd, Tb) Compounds by Optical Spectroscopy and Electronic‐Structure Calculations

“…Recent studies have shown that the ternary intermetallic compounds of the RTX family, where the R − rare‐earth, T, and X − different d ‐ and p ‐elements, respectively, have a wide variety of magnetic and electronic properties, presenting fundamental and practical interest, see recent reviews and other studies. A number of unusual physical phenomena observed in such compounds, for example, the giant magnetocaloric effect and magnetoresistance, are considered to be related with the peculiarities of hybridization of the localized 4 f ‐states of rare‐earth metals and conduction electrons in the electronic system.…”