Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Spin Systems, Itinerant Magnets 3
TT 28.3: Vortrag
Dienstag, 12. März 2013, 10:00–10:15, H19
Studying the local magnetic induction of EuB6 by high-resolution micro-Hall magnetometry — •Merlin Pohlit1, Adham Amyan1, Jens Müller1, and Zachary Fisk2 — 1Physikalisches Institut, Goethe-Universität, Frankfurt (M), Germany — 2University of California, Irvine, USA
In the ferromagnetic semimetal EuB6 two consecutive transitions occur at Tc1=15.5 K and Tc2=12.6 K. They are related to electronic and magnetic phase separation, and bulk magnetic ordering, but the details are not yet fully understood. Recently, there has been experimental evidence for the CMR effect observed at Tc1 beeing caused by percolation of magnetic polarons [1]. Local magnetic measurements, however, have not been performed so far. In this talk we discuss local magnetic induction measurements on a high-quality single crystal using micro-Hall magnetometers based on a high-mobility 2DEG in GaAs/AlGaAs. The sample is positioned on top of the Hall device where a series of adjacent lithographically defined crosses allow for spatially-resolved measurements with micron-size resolution.
Strayfield measurements close to the sample give evidence for a spontaneous magnetisation at Tc1 and allow further insights in the field and temperature dependence of the magnetic transitions. Simultanously performed measurements below the sample give evidence for magnetic domains/inhomogeneities which seem to exist even below the second magnetic transition but vanish by application of a small external field.
[1] Das et al., Phys. Rev. B 86, 184425 (2012)