Possible antimagnetic rotation in 97,99 Mo

Background: The antimagnetic rotation (AMR) is a unique nuclear phenomenon arising from the shears mechanism, where angular momentum is generated through the gradual alignment of proton holes and neutron particles in weakly deformed nuclei. The [Formula: see text] mass region, with [Formula: see text] and [Formula: see text], has been a fertile ground for investigating AMR, particularly in Pd and Cd isotopes. However, the possible existence of AMR in neighboring Mo isotopes has remained an open question. Purpose: The present work aims to investigate the possibility of antimagnetic rotation in the negative parity bands of [Formula: see text]Mo using both the semiclassical particle-rotor model (SCM) and the extended projected shell model (PSM) approach recently developed by Tawseef et al. Methods: The SCM calculations have been performed using the twin-shears mechanism, while the PSM calculations employ the extended framework with quasiparticle excitations from two major oscillator shells and up to five-quasiparticle configurations. The PSM calculations use ground-state deformations [Formula: see text] for [Formula: see text]Mo and [Formula: see text] for [Formula: see text]Mo from the macroscopic-microscopic model of Möller and Nix. The configurations considered are [Formula: see text] for [Formula: see text]Mo and [Formula: see text] with [Formula: see text] core contribution for [Formula: see text]Mo. Results: The calculated spin versus rotational frequency ([Formula: see text]) plots show strong agreement with experimental data for both nuclei. The PSM calculations reproduce the experimental level energies with average deviations of less than [Formula: see text], validating the extended PSM approach. The spin versus rotational frequency plots reveal that [Formula: see text]Mo exhibits two level crossings at [Formula: see text] MeV and [Formula: see text] MeV, corresponding to the alignment of [Formula: see text] protons and [Formula: see text] neutrons, respectively, while [Formula: see text]Mo exhibits only one level crossing at [Formula: see text] MeV corresponding to the alignment of [Formula: see text] neutrons. The SCM and PSM-based electric quadrupole transition probabilities [Formula: see text] show a clear decreasing trend with increasing spin, decreasing from approximately [Formula: see text] at [Formula: see text] to [Formula: see text] at [Formula: see text] for [Formula: see text]Mo, and from approximately [Formula: see text] to [Formula: see text] for [Formula: see text]Mo, closely following the systematics of the well-established AMR nuclei [Formula: see text]Pd and [Formula: see text]Pd. The [Formula: see text] ratio shows a sharp increase at higher spins, increasing from approximately [Formula: see text] to [Formula: see text] for [Formula: see text]Mo and from approximately [Formula: see text] to [Formula: see text] for [Formula: see text]Mo, providing a powerful discriminant for AMR. The kinematic moment of inertia [Formula: see text] changes gradually over a wide rotational frequency range following the level crossings, which is a characteristic feature of AMR observed in Cd and Pd isotopes. Despite the presence of two level crossings in [Formula: see text]Mo and one in [Formula: see text]Mo, both nuclei exhibit all the characteristic signatures of AMR, consistent with the systematics of [Formula: see text]Pd and [Formula: see text]Pd, where the shears mechanism operates in conjunction with gradual nucleon alignment. Conclusions: The decreasing trend in [Formula: see text] with increasing spin, the sharp increase in the [Formula: see text] ratio, and the gradual evolution of [Formula: see text] provide strong evidence for the shears mechanism characteristic of antimagnetic rotation in the negative parity bands of [Formula: see text]Mo. These findings extend the systematics of antimagnetic rotation in the [Formula: see text] mass region and provide a theoretical basis for future DSAM lifetime measurements to establish firm experimental evidence in [Formula: see text]Mo nuclei.