Signature inversion and the first observation of a magnetic dipole band in odd-odd rubidium isotopes: [Formula Presented]

High-spin states in [Formula Presented] were studied through the [Formula Presented] reaction at 56 MeV beam energy via a thin target coincidence measurement. The known sequence of positive-parity states built on the [Formula Presented] state at 191.3 keV was extended up to spin 14, and signature inversion was observed around spin 11. Above spin 8 the observed properties of this band indicate a rotationlike structure. A new high-lying level sequence connected by [Formula Presented] transitions was identified. This magnetic dipole sequence is built on a new [Formula Presented] level at 2617.3 keV excitation energy which is interpreted as a [Formula Presented] four-quasiparticle state at small quadrupole deformation.