title: Singlet-triplet excitations in the unconventional spin-Peierls TiOBr compound.
abstract: We have performed time-of-flight neutron scattering measurements on powder samples of the unconventional spin-Peierls compound TiOBr using the fine-resolution Fermi chopper spectrometer (SEQUOIA) at the Spallation Neutron Source at Oak Ridge National Laboratory. These measurements reveal two branches of magnetic excitations within the commensurate and incommensurate spin-Peierls phases, which we associate with n=1 and n=2 triplet excitations out of the singlet ground state. These results represent the first direct measurement of the singlet-triplet energy gap in TiOBr, which has a value of E(g)=21.2±1.0  meV.
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Clancy
authors.forename: B D
authors.initials: BD
authors.lastname: Gaulin
authors.forename: C P
authors.initials: CP
authors.lastname: Adams
authors.forename: G E
authors.initials: GE
authors.lastname: Granroth
authors.forename: A I
authors.initials: AI
authors.lastname: Kolesnikov
authors.forename: T E
authors.initials: TE
authors.lastname: Sherline
authors.forename: F C
authors.initials: FC
authors.lastname: Chou