# Berlin 2012 – wissenschaftliches Programm

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# KR: Fachgruppe Kristallographie

## KR 6: 100 years since the Laue experiment: Topical aspects of diffraction and scattering (Joint Session KR, BP, DF, GP, MA, MI, MM; related to SYXD)

### KR 6.8: Vortrag

### Dienstag, 27. März 2012, 11:45–12:00, EMH 225

**Magnetic structure of magnetoelectric NdFe**_{3}**(BO**_{3}**)**_{4}** under applied magnetic fields** — •Jorge E. Hamann-Borrero^{1}, Sven Partzsch^{1}, Sergio Valencia^{2}, Claudio Mazzoli^{3}, Christian Hess^{1}, A. Vasiliev^{4}, L. Bezmaternikh^{5}, Bernd Büchner^{1}, and Jochen Geck^{1} — ^{1}IFW-Dresden — ^{2}Helmholtz-Zentrum-Berlin — ^{3}ESRF, Grenoble, France — ^{4}Moscow State University, Russia — ^{5}L. V. Kirensky Institute of Physics, Russian Academy of Sciences, Krasnoyarsk, Russia

The magnetic structure of the magneto-electric NdFe_{3}(BO_{3})_{4} is studied by means of Resonant X-ray Magnetic Scattering (RXS) at the Nd L_{2,3} and Fe K edges. The temperature dependent experiments show below T_{N} = 30 K the appearance of commensurate (CM) magnetic superlattice reflections with Miller indices (0,0,*l*± 3/2) (where *l*=3*n* and *n*= integer). By further cooling, at T_{ICM}∼ 16 K, a transition into an incommensurate (ICM) spin helix structure is observed in agreement with recent neutron experiments[1,2]. Detailed mean field based analysis of the x-ray diffracted intensities show, that the Nd and Fe magnetic sublattices behave differently. In fact the magnetization of the Nd sublattice is induced by the Fe moments.
At T<T_{ICM}, by applying an external magnetic field **B** parallel to the *ab*-plane, the magnetic structure suffers a reorientation transition from a spin helix configuration to a collinear structure where all the moments align perpendicular to **B** in the basal plane.

[1] M. Janoschek et al. Phys. Rev. B, 2010, 81, 094429

[2] P. Fischer et al. Jour. Phys. Cond. Matt., 2006, 18, 7975-7989(15)