Rotational bands inGd140: Systematics of triaxialN=76isotones

States up to $I^{\pi }$ ${=(20\mathrm{}}^{+}$) have been established in the neutron-deficient ${}_{}{}^{140}{}_{}{}^{}\mathrm{Gd}$ nucleus by means of the ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$ ${(}^{50}$Cr, 2pγ) reaction. At a rotational frequency ħω=0.30 MeV, the ground-state band is crossed by a band built on the aligned [π$h_{11/2}$ ${]}^2$ two-quasiproton configuration. This proton-aligned band was observed from spins ${10}^{+}$ to (${20}^{+}$). A second ${10}^{+}$ state was established which is most likely built on the [ν$h_{11/2}$ ${]}^2$ two-quasineutron configuration. The γ-vibrational band was observed up to $I^{\pi }$ ${=(8\mathrm{}}^{+}$) with the odd- and even-spin members exhibiting a pronounced signature splitting. The results are compared to those found recently for the lighter ${}_{}{}^{136}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{138}{}_{}{}^{}\mathrm{Sm}$ N=76 isotones.