Eu1 − xSrxAu4Cd2: a ferromagnetic solid solution with adjustable Curie temperature

Abstract

Samples of the solid solution Eu1–xSrxAu4Cd2 (YbAl4Mo2 type, space group I4/mmm) with x = 0.2, 0.4, 0.6, and 0.8 were synthesized from the elements by annealing in sealed tantalum ampoules. The structures of Eu0.66Sr0.34Au4.12Cd1.88 and Eu0.22Sr0.78Au4.10Cd1.90 were refined from X-ray single crystal diffractometer data. Besides the expected Eu/Sr mixing on the 2a sites the diffraction data revealed also a small degree of Cd/Au mixing on the 4d sites of the cadmium chains. Temperature dependent magnetic susceptibility data show divalent europium and ferromagnetic ground states for all samples and a linear decrease of the Curie temperature from 16.3 K for EuAu4Cd2 to 2.9 K for Eu0.2Sr0.8Au4Cd2. Magnetization isotherms characterize the Eu1 − xSrxAu4Cd2 samples as soft ferromagnets. The divalent nature of europium is underpinned by 151Eu Mössbauer spectra. The decreasing Curie temperature goes along with a decreasing magnetic hyperfine field at 6 K. Graphic abstract

The Solid Solution Eu1–xSrxAuIn

“…It is remarkable, that even for x = 0.8, corresponding to a high dilution of the europium substructure, a magnetically ordered state is still present, similar to the recently observed solid solution Eu 1– x Sr x Au 4 Cd 2 . [ 26 ]…”

“…We have recently studied the ferromagnetic europium compounds EuPtIn 2 ( T C = 32.5 K) [ 24 ] and EuAu 4 Cd 2 ( T C = 16.3 K) [ 25,26 ] with respect to their complete solid solutions Eu 1–x Sr x PtIn 2 [ 24 ] and Eu 1–x Sr x Au 4 Cd 2 . [ 26 ] Both solid solutions show Vegard‐type behavior for the course of their lattice parameters and the Curie temperatures drop almost linearly with increasing strontium content to T C = 3.1 K for Eu 0.1 Sr 0.9 PtIn 2 and to 2.9 K for Eu 0.2 Sr 0.8 Au 4 Cd 2 .…”

Gadolinium spin dilution in the solid solution Gd1–xYxAuMg – gradual decrease of the Néel temperature

“…Interesting examples are the Laves phases Gd 1-x Y x Co 2 [22] and the solid solutions Gd 1-x Y x Mn 2 Ge 2 , [23] Gd 1-x Y x TiGe [24] and Gd 1-x Y x Co 2 B 2 . [25] In continuation of our recent studies on Eu 2 + /Sr 2 + substitution [19,20,26] we have now studied gadolinium intermetallics with comparatively high ordering temperatures with respect to Gd 3 + /Y 3 + substitution. As a first example we chose the 81.1 K antiferromagnet GdAuMg.…”

“…In continuation of our recent studies on Eu 2+ /Sr 2+ substitution [19,20,26] we have now studied gadolinium intermetallics with comparatively high ordering temperatures with respect to Gd 3+ /Y 3+ substitution. As a first example we chose the 81.1 K antiferromagnet GdAuMg [27–29] .…”