Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 18: Metall-Isolator-Überg
änge in Quantensystemen I

TT 18.5: Vortrag

Donnerstag, 27. März 2003, 15:45–16:00, HSZ304

Spin-Orbital Chains in a Three-Dimensional Magnetic Insulator — •C. Ulrich¹, G. Khaliullin¹, J. Sirker², M. Reehuis³, M. Ohl^4,5, P. Pattison⁶, S. Miyasaka⁷, Y. Tokura⁷ und B. Keimer¹ — ¹Max-Planck-Institut FKF, Stuttgart — ²Theoretische Physik, Universität Dortmund — ³Hahn-Meitner-Institut, Berlin — ⁴Institut Laue-Langevin, Grenoble, France — ⁵Forschungzentrum Jülich — ⁶ESRF, Grenoble, France — ⁷University of Tokyo, Japan

Materials with valence d-electrons exhibit a multitude of competing many-body ground states whose theoretical description is still in its infancy. As a consequence of this competition, the Mott-Hubbard insulator YVO₃ exhibits a series of temperature induced phase transitions between states with different spin and orbital ordering patterns. Neutron spectroscopy reveals a highly unusual magnetic structure and dynamics in YVO₃, whose origin is shown to lie in strong one-dimensional quantum fluctuations of both spins and orbitals. A detailed, quantitative description of the neutron data is obtained by numerically computing the spin and orbital correlation functions of a realistic one-dimensional model. This opens a new avenue for the investigation of quantum systems with orbital degeneracy.