Accepted Tuesday Nov 03, 2009
A systematical study of neutron-rich even-even Fe isotopes with neutron number 32 - 42 is carried out by using the Projected Shell Model. Calculations are performed up to spin I=20 state. Irregularities found in the yrast spectra and in B(E2) values are discussed in terms of neutron excitations to the high-j orbital g9/2. Furthermore, the neutron two-quasiparticle structure of a low-K negative-parity band and the proton two-quasiparticle structure of a high-K positive-parity band are predicted to exist near the yrast region. Our study reveals a soft nature for the ground state of N 40 isotopes and emphasizes the important role of the neutron g9/2 orbital in determining the structure properties for both low- and high-spin states in these nuclei.