Low-Temperature Magnetism in the Honeycomb Systems SrRE2O4
Vendredi 2 décembre 2016 15:00
- Duree : 1 heure
Lieu : ILL 4, Seminar Room (no 163), 71 avenue des Martyrs - Grenoble
Orateur : Oleg PETRENKO (University of Warwick - Coventry - UK)
Magnetic systems often exhibit competing magnetic interactions, that is, interactions that do not all favour the same ordered state. Sufficiently strong competition leads to new physics that is manifested by the appearance of noncollinear or incommensurate ordering, novel critical exponents and rich phase diagrams. In such highly frustrated magnetic systems the ground state may remain disordered even at zero temperature. The last two decades have seen a sustained interest in the physics of frustrated magnets both from theoreticians and experimentalists alike.
In this talk I review recent experimental studies of four members of the SrRE2O4 family, RE= Er, Dy, Ho and Gd. The RE ions in these compounds are linked in a network of triangles and hexagons. By combining bulk property measurements with neutron scattering methods we have been able to make progress in understanding the unusual physics arising from geometrically frustrated magnetism in these compounds. Neutron diffraction reveals that the magnetic order in SrEr2O4 has two components, a long-range k=0 ordered structure and a short-range ordered incommensurate structure associated with strong diffuse scattering. In SrHo2O4, the situation is similar to SrEr2O4, although the k=0 structure has a limited correlation range. We find that SrDy2O4 remains magnetically disordered down to 50 mK while SrGd2O4 demonstrates on cooling two phase transitions at 2.73 and 0.48 K.
The magnetisation process in all SrRE2O4 compounds appears to be rather remarkable even in the context of the unconventional phase transitions observed in other geometrically frustrated systems.
Contact : dubouloz@ill.fr
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