Tytuł pozycji:
High-Pressure Mössbauer Studies of Magnetism in ScFe$\text{}_{2}$ and Sc$\text{}_{0.4}$Ti$\text{}_{0.6}$Fe$\text{}_{2}$ Laves Phases
We report on $\text{}^{57}$Fe-Mössbauer studies of the magnetic properties in ScFe$\text{}_{2}$ and Sc$\text{}_{0.4}$Ti$\text{}_{0.6}$Fe$\text{}_{2}$ performed as a function of pressure and temperature. Both systems crystallize in the C14-type Laves phase structure with two different Fe sites 6h and 2a. The ferromagnetic properties of ScFe$\text{}_{2}$ (T$\text{}_{C}$=540 K at ambient pressure) change around 30 GPa to antiferromagnetic order of the 6h sites with non-magnetic 2a sites. The ordering temperature is lowered to T$\text{}_{N}$=300 K at 51 GPa. This pressure-dependent behaviour of ScFe$\text{}_{2}$ resembles that observed within the Sc$\text{}_{1-x}$Ti$\text{}_{x}$Fe$\text{}_{2}$ series as a function of x. In ferromagnetic Sc$\text{}_{0.4}$Ti$\text{}_{0.6}$Fe$\text{}_{2}$ we observe, as a function of temperature and of pressure, an abrupt high-moment to low-moment transition of the Fe band moments of the 6h sites, accompanied by a rearrangement of the spin directions. In both systems the decrease in the Fe moments is accompanied by a strong increase in the volume coefficient of the isomer shift, originating from a reduced s-electron shielding capability of the d-electrons in the low-moment state.