Magnetic dipole response in nuclei at the N=28 shell closure: a new look

The magnetic dipole response of N=28 isotones is obtained for 48Ca, 50Ti, 52Cr and 54Fe by means of shell model calculations in the full pf-shell. Spin quenching factors derived in all four nuclei by comparison to experimental strengths from electron scattering agree well with each other. The deduced effective g-factor gseff=0.75(2) gsfree is consistent with findings for the Gamow-Teller strength in this mass region. The ability of state-of-the-art shell-model calculations to describe the gross properties and the fragmentation of the complex experimental B(M1) strength distributions is investigated.