High-Moment-Low-Moment Description of Magnetovolume Effects in Y(Mn x Al 1− x ) 2 and Y x Sc 1− x Mn 2
Based on the assumption of a high-moment-low-moment instability of the Mn atom, we construct a simple spin model with coupled magnetic and spatial degrees of freedom to describe the Laves phase systems Y(Mn x Al 1 m x ) 2 and Y x Sc 1 m x Mn 2 . Monte Carlo simulations of this model qualitatively reproduce anomalies observed in these materials like a discontinuous giant volume change and anomalous thermal expansion behavior.
Effect of pressure on the Néel temperature of YMn2: resistivity of Y(Mn1−xCux)2
Abstract Resistivity measurements have been carried out for Y(Mn1−xCux)2 compounds with values of x of 0, 0.04, 0.07, 0.10, 0.20 and 0.30 in the temperature range from 4.2 up to 300 K at zero pressure and for YMn2 under a pressure of 2 kbar. TN has been found to decrease rapidly by applying external pressure as well as by applying a chemical pressure caused by a partial substitution of Mn atoms by Cu atoms.
High-field magnetisation of Nd1−xLuxMn2 compounds
Abstract Nd 1− x Lu x Mn 2 compounds with x =0, 0.02, 0.03, 0.05, 0.10, 0.15, 0.20, 0.30 and 1.0 have been investigated in high-field magnetisation measurements up to 38 T at 4.2 K and in electrical resistivity, thermal expansion and specific heat experiments between 1.5 K and room temperature. The high-field magnetisation increases linearly with increasing field for LuMn 2 with a susceptibility of 11 × 10 -9 m 3 / mol , indicating a paramagnetic behaviour. No anomalies are observed in other experiments in the temperature range from 1.5 to 300 K, confirming this observation. For the compounds with x ⩽0.20, saturation is not reached in the highest field whereas around 10 T a transition in the magnetisation curve is observed. For the compound with x =0.30, the magnetisation shows a trend to saturation at higher field values. The value of the saturated moment in this case is close to that expected for Nd 3+ which suggests the absence of a Mn moment in this compound. This result is confirmed by other experimental data.