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Silvie Mašková: Hydrogen as a probe into f-magnetism
May 2, 2019 @ 14:00 - 15:00
Thursday, 2.5. 2019, 14.00,
Lecture room F2 (1st floor), MFF UK, Ke Karlovu 5
Department of Condensed Matter Physics, Charles University, Prague, The Czech Republic
Hydrogen as a probe into f-magnetism
The sensitivity of the interactions in the intermetallic systems to modification of the crystal structure makes the experimental techniques involving alternation of the atomic arrangement especially important. Various studies under compression are well-known examples of such methods. From this point of view hydrogenation can be treated as a complementary technique that provides „negative“ pressure. The hydrides can be defined as compounds for which the hydrogen absorption leads to the modifications of the crystal structure, such as pure lattice expansion or the formation of a new structure. As a result, the new compounds (hydrides) exhibit qualitatively new physical properties and such modifications provide us with additional information on the peculiarities of interatomic interactions in the initial compounds.
We have been studying some members of large family of A2T2X (A = Rare-Earth (RE) or actinide, T = transition metal, X = p-metal) compounds crystallizing in the tetragonal Mo2FeB2 structure type (space group P4/mbm). U2T2X interact with H2 only at high pressure (≈ 100 bar) reaching 2 H/f.u. The H absorption produces a lattice expansion, while the tetragonal structure is preserved. On the other hand, it was found that some RE2T2X compounds can absorb much more hydrogen compared to their U-counterparts in much lower H pressures.
The impact of hydrogen absorption on crystal structure and magnetic properties of selected 4f– and 5f-compounds will be discussed.