R. Mullmann et al., EU-151 MOSSBAUER SPECTROSCOPIC, ELECTRIC, AND MAGNETIC MEASUREMENTS OF EUAGGE AND EUAUGE, Hyperfine interactions, 108(4), 1997, pp. 389-400
The physical properties of EuAgGe and EuAuGe, the structures of which
are derived from the CeCu2 type, have been investigated in detail by m
eans of magnetic susceptibility, electrical conductivity and Eu-151 Mo
ssbauer measurements. Above 50 K both germanides show Curie-Weiss beha
vior with experimental magnetic moments of mu(exp) = 7.70(5) mu(B) (Eu
AgGe) and mu(exp), = 7.40(5) mu(B) (EuAuGe) and Weiss constants of -2(
1) K (EuAgGe) and 33(1) K (EuAuCe). For EuAgGe, a magnetic phase trans
ition is observed below 18(1) K. Zero-field cooling and field cooling
measurements indicate cluster glass behavior (weak ferromagnetism, mic
tomagnetism). Magnetization measurements at 5 K show a saturation magn
etic moment of 3.3(2) mu(B)/Eu at 5.5 T. Eu-151 Mossbauer measurements
show a Eu(II) valence state (delta = -10.4 mm/s). While magnetic hype
rfine splitting appears in the spectra at temperatures as high as 15 K
, complete magnetic ordering is not reached at temperatures down to 4.
2 K. EuAuGe orders ferromagnetically at 32.9(2) K. Magnetization measu
rements at 2 K show a saturation magnetic moment of 6.2(1) mu(B)/EU at
5.5 T, respectively indicating that all spins are ordered ferromagnet
ically at low temperatures. (EU)-E-151 Mossbauer measurements show a E
u(II) valence state (delta = -10.6 mm/s) and two spectral components i
n an approximate 1:1 ratio, subjected to magnetic hyperfine splitting
effects at T-1 = 32(2) and T-2 = 18(4) K, respectively. Thus, the tran
sition temperature of 32.9 K observed in the susceptibility measuremen
ts appears to be associated with ordering of only one of the two cryst
allographical ly distinct europium sites in this compound. Electrical
conductivity measurements indicate metallic behavior for both germanid
es.