Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 19: Correlated Electrons: Low-dimensional Materials
TT 19.11: Vortrag
Dienstag, 28. März 2006, 16:45–17:00, HSZ 301
Magnetic properties of Vanadium Oxide Nanotubes — •I. Hellmann1, R. Klingeler1, E. Vavilova1,2, Y. Arango1, A. Popa1, V. Kataev1, Ch. Täschner1, and B. Büchner1 — 1Leibniz-Institute for Solid State and Materials Research IFW Dresden, Germany — 2Kazan Physical Technical Institute, RAS, Kazan, Russia
A new class of nanoscale low-dimensional magnets, mixed valent
vanadium-oxide multiwall nanotubes (VOx-NTs), shows up diverse
properties ranging from spin frustration and semiconductivity to
ferromagnetism by doping with either electrons or holes [1]. To
obtain insights into the magnetic properties of these novel
nanosize magnets we have studied the static magnetisation M of
undoped VOx-NTs in the temperature range from 2 K to 600 K in
magnetic fields up to 14 T. The data provide evidence for the
occurrence of two magnetically nonequivalent vanadium sites in the
structure. These sites can be presumably attributed to
V4+(d1, S=1/2) ions in the octahedral and tetrahedral
oxygen coordination, respectively. The former are strongly
antiferromagnetically correlated and exhibit some signatures of a
spin-liquid behaviour. The latter are much weaker magnetically
coupled and dominate the low-temperature static magnetic response.
In addition to M(H,T) measurements we present also ESR and NMR
results obtained on the same samples and discuss possible models
of spin coupling and low-energy spin dynamics in VOx-NTs.
[1] L. Krusin-Elbaum et al., Nature 431, 672 (2004)