Microscopic analysis of low-energy spin and orbital magnetic dipole excitations in deformed nuclei

A low-energy magnetic dipole $(M1)$ spin-scissors resonance (SSR) located just below the ordinary orbital scissors (OSR) was recently predicted in deformed nuclei within Wigner function moments (WFM) approach. We analyze this prediction using fully self-consistent Skyrme quasiparticle random phase approximation (QRPA) method. forces SkM*, SVbas, and SG2 are implemented to explore SSR OSR $^{160,162,164}\mathrm{Dy}$ $^{232}\mathrm{Th}$. Accuracy of method is justified by a good description $M1$ spin-flip giant resonance. The calculations show that isotopes indeed have at 1.5--2.4 MeV (below OSR) ${I}^{\ensuremath{\pi}}K={1}^{+}1$ states with large spin strength ($K$ projection total nuclear moment symmetry $z$ axis). These almost exhausted $pp[411\ensuremath{\uparrow},411\ensuremath{\downarrow}]$ $nn[521\ensuremath{\uparrow},521\ensuremath{\downarrow}]$ configurations corresponding $pp[2{d}_{3/2},2{d}_{5/2}]$ $nn[2{f}_{5/2},2{f}_{7/2}]$ structures spherical limit. So actually reduced low-orbital ($l=2,3$) states. Following our analysis contradiction WFM picture, deformation not principle origin but only factor affecting their features. strengths generally mixed exhibit interference: weakly destructive range strongly constructive range. In $^{232}\mathrm{Th}$, very small. Two groups ${I}^{\ensuremath{\pi}}={1}^{+}$ observed experimentally 2.4--4 2--4 $^{232}\mathrm{Th}$ mainly explained fragmentation strength. Distributions currents QRPA partly correspond isovector orbital-scissors flow one.