Browsing by Author "Lin, H.-J."

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Orbital ordering of layered manganites from resonant soft X-ray scattering
(2007-03-01)
Chao, K. S.
;
Huang, D. J.
;
Okamoto, J.
;
Lin, H.-J.
;
Hsu, C.-H.
We present measurements of Mn L-edge resonant soft X-ray scattering on single-layered manganites with different sizes of cations. Orbital ordering of Pr0.5Ca1.5MnO4 exhibits a stronger three-dimensional character and a dramatically enhanced transition temperature, as compared with those of La0.5Sr1.5MnO4. The c-axis correlation length of orbital ordering in Pr0.5Ca1.5MnO4 is about half of the inplane correlation length. Our results indicate that reduction in one-electron bandwidth and quenched disorder strongly enhances the stabilization of charge-orbital ordering. (c) 2006 Published by Elsevier B. V.
Orbital polarization and Jahn-Teller distortion of strained La0.5Sr0.5MnO3 thin films
(2007-03-01)
Wu, W. B.
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Huang, D. J.
;
Huang, C.-M.
;
Hsu, C.-H.
;
Chang, C. F.
We report spectroscopic evidence for orbital-mediated phases in strained La0.5Sr0.5MnO3 thin films by combining soft X-ray spectroscopy and synthesis of manganite thin films. Measurements of polarization-dependent soft X-ray absorption reveal that electronic states responsible for the lowest-energy excitations in C-type antiferromagnetic La0.5Sr0.5MnO3 films have an orbital symmetry of 3z(2) - r(2), while those in A-type AFM. films have an orbital symmetry of x(2)-y(2). Such orbital polarizations in strained films of manganite result from a combined effect of the Jahn-Teller distortion and the electron correlations of Mn 3d electrons. (c) 2006 Published by Elsevier B.V.