Tuesday, June 25, 2013

1306.5563 (S W Lovesey et al.)

Melting of chiral order in terbium manganate (TbMnO3) observed with
resonant x-ray Bragg diffraction

S W Lovesey, V Scagnoli, M Garganourakis, S M Koohpayeh, C Detlefs, U Staub
Resonant Bragg diffraction of soft, circularly polarized x-rays has been used to observe directly the temperature dependence of chiral-order melting in a motif of Mn ions in terbium manganate. The underlying mechanism uses the b-axis component of a cycloid, which vanishes outside the polar phase. Melting is witnessed by the first and second harmonics of a cycloid, and we explain why the observed temperature dependence is different in the two harmonics. Our direct observation of melting is supported by a solid foundation of evidence, derived from extensive studies of the azimuthal-angle dependence of intensities with both linear and circular polarization.
View original: http://arxiv.org/abs/1306.5563

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