Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 3: Anisotropie / Magnetoelastizit
ät

MA 3.3: Vortrag

Montag, 8. März 2004, 12:30–12:45, H10

Strong change of the crystal structure of Tb_0.5Dy_0.5Cu₂ induced by an external magnetic field — •Sebastian Raasch^1,2, Mathias Doerr¹, Martin Rotter³, Andreas Kreyssig¹, Jens-Uwe Hoffmann², Ulrike Witte^1,2, and Michael Loewenhaupt¹ — ¹TU Dresden, Institut fuer Festkoerperphysik, Germany 01062 Dresden — ²Hahn Meitner Institut Berlin — ³Universitaet Wien, Institut fuer physikalische Chemie

Magnetic fields of 4 T applied to a single crystal Tb_0.5Dy_0.5Cu₂ along the (magnetic hard) c axis affect a change of the crystalline structure. Concurrently the symmetry axes change. Neither decreasing the magnetic field to zero nor warming up the crystal to room temperature led to a virgin state crystal. Further a change of the magnetic anisotropy has been observed. This behaviour, which was also observed at similar orthorhombic RCu₂ (R = Rare Earth) compounds, can not be explained only by a competition of single ion and exchange anisotropy.

In our recent neutron-scattering experiment at the E2 flat cone diffractometer of the HMI Berlin we proved, that this structural conversion is associated with the decay of the single-domain crystal into three (crystallographic) variants, rotated by 60 degrees within the pseudo hexagonal ac-plane. Models of the converted crystal structure are compared to the results of the experiment.