Gamow-Teller (GT) strength distributions of Mg isotopes are investigated
within a framework of the deformed quasi-particle random phase
approximation(DQRPA). We found that the N=20 shell closure in 28∼34Mg
was broken by the prolate shape deformation originating from the {\it
fp}-intruder states. The shell closure breaking gives rise to a shift of
low-lying GT excited states into high-lying states. Discussions regarding the
shell evolution trend of single particle states around N=20 nuclei are also
presented with the comparison to other approaches.Comment: 5 pages, 5 figures. arXiv admin note: text overlap with
arXiv:1206.2156. text overlap with arXiv:1206.215