- Silvie Mašková: Magnetic properties and structure diversity in RE2T2Mg hydrides
- 20. 5. 2015, 14:50
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
We have been studying several RE2Ni2Mg compounds crystallizing in tetragonal Mo2FeB2 structure (P4/mbm). In this structure, RE atoms form a triangular motif bringing magnetic frustration into the system. As a consequence the magnetization typically shows several metamagnetic transitions. Magnetic properties are highly dependent on the exchange interactions between nearest (N) and next-nearest (NN) neighbors. Considering the role of the balance between the N- and NN-exchange we have decided to use the hydrogenation as the tool for weakening their absolute and relative strengths. It was found that these compounds tend to absorb up to 8 H/f.u. The crystal structure is changed to monoclinic structure (space group P21/c). The magnetic ordering temperatures of all RE-compounds studied are dramatically reduced by the hydrogenation. Such general dramatic weakening of the RKKY exchange interaction should have a strong reason most likely the impact of hydrogenation on the system of conduction electrons. The RE2Ni2Mg compounds studied will be compared with isostructural RE2Pd2Mg which yield different types of hydrides.