Synthesis and magnetic properties of cubic laves phase compounds YFeCu, GdFeCu and Yb(Fe1 − vCuv)2

High pressure synthesis of a new phase of YbAg2: Structure, valence of Yb and properties

“…This observed disagreement between the experiments and the ab initio calculations was attributed [8] to an extremely high sensitivity of the crystal structure to non-hydrostatic compression, which together with a possible kinetic frustration is the main reason for the suppression of the transition to the energetically favorable MgCu 2 -type structure. Indeed, it was found [9] that at high pressure (8 GPa) and high temperature (T ≈ 1600 o C), the compound YbCu 2 crystallizes in the hexagonal Laves phase (type MgZn 2 ). L III -Yb absorption edge at 80K is shown in Fig.…”

“…The appearance of a long range magnetic order below 0.5 K can be discarded as the specific heat C(T) itself continues to decrease down to the lowest temperature of our measurements (0.5 K). Note, that the appearance of a stable long range magnetic order at low temperature requires the valence of Yb ion to be +3 [9,10] which is not the case in YbAg 2 . The most probable reason of the specific heat anomaly is the presence of spin fluctuations at low temperature which may appear when the valence approaches the +3 value on cooling.…”