Regensburg 2016 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 42: Correlated Electrons: Frustrated Magnets - Cu-based Systems & FeCr
TT 42.3: Talk
Wednesday, March 9, 2016, 10:00–10:15, H18
Substitutions in Cu-based frustrated spin-systems: BaCuSi2O6 and ZnCu3(OH)6Cl2 — •Pascal Puphal1, Denis Sheptyakov2, Natalija Van Well2, Raivo Stern3, Lars Postulka1, Bernd Wolf1, Michael Lang1, and Cornelius Krellner1 — 1Physikalisches Institut, Goethe Universität Frankfurt, Germany — 2PSI, Switzerland — 3National Institute of Chemical Physics and Biophysics, Estonia
BaCuS2O6 is a spin dimer system presenting a 2D Bose-Einstein condensation of triplons at low temperatures and high magnetic fields. We present a structural analysis of the substituted system (Ba1−xSrx)CuSi2O6, which reveals a stable tetragonal crystal structure down to 2 K unlike its parent compound x = 0. We explore the structural details with low-temperature neutron and synchrotron powder diffraction, room-temperature NMR, as well as magnetic- and specific-heat measurements.
ZnCu3(OH)6Cl2 is a highly frustrated kagomé system,
which has a antiferromagnetic superexchange interaction of J = 17
meV, but no magnetic transition or long-range order has been observed
down to T = 50 mK. We present first results of MxCu4−x(OH)6Cl2,
with a three valent ion M, which should lead to a Dirac metal as proposed
by I. I. Mazin et. al. [1]. We could synthesize a Paratacamite-type
(x < 1), which shows a magnetic ordering below 6.5 K. This transition
can be decreased with increasing x.
[1] I. I. Mazin et. al., Nature Communications 5, 4261 (2014)