Shell evolution of N=20 nuclei and Gamow-Teller strengths of ³⁰,³²,³⁴Mg by the deformed QRPA

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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 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.