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TT: Fachverband Tiefe Temperaturen

TT 9: Correlated Electrons: Metal-Insulator Transition 1

TT 9.8: Vortrag

Montag, 23. März 2009, 16:00–16:15, HSZ 03

Crystal-field level inversion in lightly Mn-doped Sr₃Ru₂O₇ — Muhammed A. Hossain¹, Zhiwei Hu², Maurits W. Haverkort², •Tobias Burnus², Chun Fu Chang², Stefan Klein², Jonathan D. Denlinger³, Hong-Ji Lin⁴, Chien Te Chen⁴, Roland Mathieu⁵, Y. Kaneko⁵, Yoshinori Tokura⁵, S. Satow⁵, Y. Yoshida⁶, Hidenori Takagi⁵, Arata Tanaka⁷, Ilya S. Elfimov¹, George A. Sawatzky¹, L. Hao Tjeng², and Andrea Damascelli¹ — ¹University of British Columbia, Vancouver, Canada — ²II. Physikalisches Institut, Universität zu Köln — ³Advanced Light Souce, Berkeley, California — ⁴National Synchrotron Radiation Research Center, Hsinchu, Taiwan — ⁵University of Tokyo, Japan — ⁶National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan — ⁷Hiroshima University, Japan

Sr₃(Ru_1−xMn_x)₂O₇, in which 4d-Ru is substituted by the more localized 3d-Mn, is studied by x-ray dichroism and spin-resolved density functional theory. We find that Mn impurities do not exhibit the same 4+ valence of Ru, but act as 3+ acceptors; the extra e_g electron occupies the in-plane 3d_x²−y² orbital instead of the expected out-of-plane 3d_3z²−r². We propose that the 3d–4d interplay, via the ligand oxygen orbitals, is responsible for this crystal-field level inversion and the material’s transition to an antiferromagnetic, possibly orbitally ordered, low-temperature state.