Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 44: Poster Session Correlated Electrons

TT 44.43: Poster

Thursday, March 17, 2011, 10:00–13:00, P1

Charge, orbital and spin ordering in 214- manganites, nickelates and cuprates investigated by neutron and x-ray scattering — •A. Bielefeld¹, H. Ulbrich¹, D. Senff¹, A. C. Komarek¹, P. Steffens², Y. Sidis³, and M. Braden¹ — ¹II. Phys. Institut, Universität zu Köln — ²ILL, Grenoble (France) — ³LLB, Saclay (France)

The coupling of charges and magnetic moments in numerous transition-metal compounds leads to a complex ordering with checkerboard or stripe like patterns. For nickelates and cuprates stripe states has been intensively studied particularly due to the possible implications for high T_c superconductivity. We have studied the mixed order of electronic, orbital and magnetic degrees of freedom in the planar compounds La_2−xSr_xReO₄ (Re = Mn, Ni, Cu). For the manganites we have examined half (x=0.5), electron-doped (x<0.5) and overdoped (x>0.5) systems. For x=0.5, the equal amount of Mn³⁺ and Mn⁴⁺ ions leads to a checkerboard ordering of charges. The spins of the Mn³⁺ and Mn⁴⁺ order in an antiferromagnetic CE-type structure following the orbital order [1-3]. For the overdoped-system we find an incommensurate stripe-like coupling of four order parameters: charges, orbitals and magnetic ordering of Mn³⁺ and Mn⁴⁺ [4]. The formation of stripes in overdoped manganites is similar to stripe phases in nickelates. In 214-cuprates, incommensurate magnetic ordering leads to the forming of diagonal stripes.
J.B. Goodenough, Phys. Rev. 100, 564 (1955).
D. Senff et al., Phys. Rev. Lett. 96, 257201 (2006).
D. Senff et al., Phys. Rev. B 77, 184413 (2008).
H. Ulbrich et al., arXiv: 1008.4496