Evidence of antimagnetic rotation in odd- A Cd 105

The lifetimes of the levels above spin $23/{2}^{\ensuremath{-}}$ in the negative-parity yrast band of $^{105}\mathrm{Cd}$ have been measured using the Doppler shift attenuation method. The obtained $B(E2)$ values are small and show a decrease with an increase in spin. This establishes, for the first time, antimagnetic rotation (AMR) in an odd-$A$ nucleus. An excellent agreement between the theoretical (semiclassical model) and experimental results along with a large ${\mathcal{I}}^{(2)}/B(E2)$ ratio for the states strongly suggests that the structure of the levels beyond spin $23/{2}^{\ensuremath{-}}$ has the character of a twin-shears type AMR band resulting from the coupling of a pair of ${g}_{9/2}$ proton holes with aligned ${h}_{11/2}$ and $({g}_{7/2}){}^{2}$ neutron particles, along with a small contribution from the core rotation.