Talks and Poster Presentations (without Proceedings-Entry):
H. Michor, H. Rosner, M. Doerr, J. Perenboom, M. Rotter, W. Schnelle, U. Schwartz, E. Bauer, G. Hilscher:
"Itinerant magnetism and magneto-volume coupling in YCo9Si4 and LaCo9Si4";
Talk: International Workshop on Exotic States in Materials with Strongly Correlated Electrons,
YCo9Si4 exhibits a weak itinerant ferromagnetism below TC = 25 K and an ordered moment of 1.4 μB/f.u. Isostructural LaCo9Si4 on the other hand is a strongly exchange Pauli paramagnet which exhibits itinerant electron metamagnetism above 3T. The paramagnetic ground state of the latter is counter-intuitive because of the larger unit cell volume as compared to YCo9Si4 and appears inconsistent with ab initio studies indicating that both compounds shall have a ferromagnetic ground state. A possible explanation for these disagreements may be strong spin-fluctuations which are clearly revealed by transport properties but not taken into account in the electronic structure studies. We thus performed pressure dependent resistivity measurements on YCo9Si4 and pressure dependent magnetisation measurements on LaCo9Si4. The studies reveal a negative dTC/dp for YCo9Si4 and an initial increase of the metamagnetic critical field for LaCo9Si4; i.e., a positive magneto-volume coupling in both cases. The latter is corroborated by forced magneto-striction studies on YCo9Si4 as well as LaCo9Si4 and is in line with LDA calculations yielding a gradual reduction of the ordered moment as the volume is reduced.
Created from the Publication Database of the Vienna University of Technology.