  Magnetic dipole strength functions are determined for the series of germanium
isotopes from $N = Z = 32$ to $N$ = 48 on the basis of a large number of
transition strengths calculated within the shell model. The evolution of the
strength with increasing neutron number in the $1g_{9/2}$ orbital is analyzed.
A bimodal structure comprising an enhancement toward low transition enery and a
resonance in the region of the scissors mode is identified. The low-energy
enhancement is strongest near closed shells, in particular at the almost
completely filled $1g_{9/2}$ orbital, while the scissorslike resonance is most
pronounced in the middle of the open shell, which correlates with the magnitude
of the also deduced electric quadrupole transition strengths. The results are
consistent with previous findings for the shorter series of iron isotopes and
proves the occurrence and correlation of the two low-lying magnetic dipole
modes as a global structural feature.
