Berlin 2012 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 2: Multiferroics I (jointly with MA, DS, KR, TT)
DF 2.9: Vortrag
Montag, 26. März 2012, 12:00–12:15, EB 301
Manipulation of the antiferromagnetic structure in LiNi(1−x)FexPO4 (x = 0.03, 0.2) by iron substitution — •Anne Zimmermann1 and Manfred Fiebig1,2 — 1HISKP, University of Bonn, Germany — 2Materials Department, ETH Zurich, Switzerland
The LiMPO4 system (M = Fe, Ni, Co, Mn) includes crystallographically isostructural compounds with antiferromagnetic (AFM) order differing in the spin direction only. Thus, the system offers the opportunity to study fundamental mechanisms of AFM 180∘ domain formation in a range of similar but not identical compounds.
In order to investigate the interplay between the different types of spin order LiNi(1−x)FexPO4 samples with different mixing ratios of nickel and iron were studied using optical second harmonic generation (SHG). SHG coupling linearly to the AFM order parameter was identified in spectroscopy measurements and used for domain imaging. A small iron substitution of x = 0.03 yields no change in the domain pattern as well as in the magnetic structure in contrast to pure LiNiPO4. However, for an iron substitution of x = 0.2 the spin structure changes significantly: the spin direction lies in the yz-plane and thus between the two spin directions for LiNiPO4 and LiFePO4. The change in magnetic structure is revealed in a different domain pattern as well. Furthermore the order parameter exhibits an unsual, photosensitive temperature dependence which is discussed in detail.
- Work supported by the SFB 608 of the DFG.