Configuration-dependent band structures in odd-odd ${}^{180}\mathrm{Ir}$

High-spin states in ${}^{180}\mathrm{Ir}$ have been investigated by means of in-beam $\gamma$-ray spectroscopy techniques with the ${}^{154}\mathrm{Sm}{(}^{31}\mathrm{P},5n\gamma {)}^{180}\mathrm{Ir}$ reaction. Excitation functions, $x-\gamma$ and $\gamma -\gamma -t$ coincidences, DCO (directional correlation of $\gamma$ rays deexciting oriented states) ratios, and intraband $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios were measured. Five rotational bands have been identified and their configurations are proposed on the basis of $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios and by comparing the band properties with known bands in neighboring odd-mass and even-mass nuclei. The neutron $\mathrm{AB}$ crossing is observed at $ħ{\omega }_c=0.26\mathrm{}\left(1\right)\mathrm{}\hspace{0.5em}\mathrm{MeV}$ for the $\pi {1/2}^{-}\left[541\right]\otimes \nu {1/2}^{-}\left[521\right]$ and $\pi {1/2}^{-}\left[541\right]\otimes \nu {5/2}^{-}\left[512\right]$ bands, respectively. Staggering of levels as a function of the number of neutron pairs is revealed in the $\pi {1/2}^{-}\left[541\right]\otimes \nu {1/2}^{-}\left[521\right]$ doubly decoupled bands of ${}^{178–186}\mathrm{Ir}.$ The gradual alignment gains at low rotational frequencies are observed in the two strongly coupled bands. Band crossings and alignments in ${}^{180}\mathrm{Ir}$ are discussed with reference to the total Routhian surface and cranked shell model calculations performed for the neighboring odd-mass nuclei.