Hamburg 2001 – scientific programme
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TT: Tiefe Temperaturen
TT 11: Fachsymposium: Eindimensionale Übergangsmetalle
TT 11.8: Talk
Tuesday, March 27, 2001, 18:00–18:15, A
Phonons and magnetic excitations of the antiferromagnetic spin-chain compound (VO)2P2O7 — •Uwe Kuhlmann1, Christian Thomsen1, A.V. Prokofiev2, Frank Büllesfeld2, E. Uhrig2, M. Anton2, and W. Assmus2 — 1Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — 2Physikalisches Institut, Universität Frankfurt, D-60054 Frankfurt, Germany
We examined the alternating antiferromagnetic (AF) spin-chain compound (VO)2P2O7 by Raman and infrared spectroscopy. The ambient pressure (AP) phase of (VO)2P2O7, which crystallizes in the orthorhombic system Pca21, reveals two different spin-gap energies in the Raman spectra. They originate from two independent AF spin chains in the unit cell, as already suggested by inelastic neutron scattering and susceptibility measurements. (AP)-(VO)2P2O7 shows a strong spin-phonon coupling of some vibrational modes and an unusual temperature behavior of others. The high pressure phase (HP) of (VO)2P2O7 has a higher symmetry (Pnab) and, as expected, we find that in comparison to the AP-phase most modes are degenerate.