Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Magnetic Materials

MA 10.6: Vortrag

Montag, 25. Februar 2008, 16:30–16:45, H 1028

Incommensurate Spin Ordering and Fluctuations in Underdoped La_2−xBa_xCuO₄ — •Sarah Dunsiger¹, Yang Zhao², Bruce Gaulin², Hanna Dabkowska², Zahra Yamani³, William Buyers³, Yiming Qiu⁴, John Copley⁴, Yvan Sidis⁵, and Philippe Bourges⁵ — ¹Physics Department E21, Technical University of Munich, D-85748 Garching, Germany — ²Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada — ³Canadian Neutron Beam Centre, NRC, Chalk River Laboratories, Chalk River, ON, Canada — ⁴National Institute of Standards and Technology, Gaithersburg, Maryland, USA. — ⁵Laboratoire Léon Brillouin, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France.

The diverse magnetic properties of the La_2−x(Sr,Ba)_xCuO₄ transition metal oxides may be tuned in a controllable way by doping with mobile holes. In one interpretation, the holes are believed to organise into correlated static or dynamic stripes. We report the first observation of static incommensurate spin ordering in underdoped La_2−xBa_xCuO₄ (x=0.025, 0.05, 0.08) using neutron diffraction. Elastic collinear incommensurate peaks are observed below the superconducting transition (T_C ∼ 27 K) in La_2−xBa_xCuO₄ (x=0.08). In marked contrast, diagonal satellite peaks have been observed at low temperature in positions rotated by 45^∘ within the (HK0) plane for La_2−xBa_xCuO₄ (x∼ 0.025, 0.05). Our neutron scattering results are compared with analogous studies on La_2−xSr_xCuO₄ which indicate that such a rotation of the spin structure may be a generic feature of the underdoped La-214 cuprates.