Structure of energy level degeneracy of a single-spin model from a view point of symmetry of the spin anisotropy and its nontrivial spin($S$)-dependence on the higher order anisotropy
| dc.creator | Hijii, Keigo | |
| dc.creator | Miyashita, Seiji | |
| dc.date | 2009-05-18 | |
| dc.date | 2009-05-19 | |
| dc.date.accessioned | 2026-07-07T13:15:57Z | |
| dc.date.available | 2026-07-07T13:15:57Z | |
| dc.description | We study structure of the gapless points (diabolical points) at zero magnetic field ($H_z=0$) of single-spin models with spin anisotropies. Nontrivial appearance of diabolical points at finite transverse field $H_x$ has been studied from the view point of interference of the Berry phase, and related phenomena have been experimentally found in the single molecular magnet Fe$_8$. We study effects of the orthorhombic single-ion anisotropy $E(S_+^2+S_-^2)$ and find a symmetry associated with the degeneracy, which provides a clear picture of the global structure of energy level diagram including the excited states. Moreover, we study effects of the higher order anisotropy $C(S_+^4+S_-^4)$, and find that, in contrast to the semiclassical limit $(S\to\infty)$, location of a pair annihilation of the diabolical point does not coincides with a point at which a pair of diabolical points appears in nonzero $H_y$ space(bifurcation points). Distance between the annihilation and bifurcation points vanishes when $S\to\infty$, which restores the semiclassical result. We obtain a complete structure of the diabolical points in the $(C,H_x)$ plane. | |
| dc.identifier | https://arxiv.org/abs/0905.2780 | |
| dc.identifier | http://arxiv.org/abs/0905.2780 | |
| dc.identifier | Physical Review B, Vol.78, No.21, 214434 (2008) | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/230639 | |
| dc.subject | Mesoscale and Nanoscale Physics | |
| dc.subject | Statistical Mechanics | |
| dc.title | Structure of energy level degeneracy of a single-spin model from a view point of symmetry of the spin anisotropy and its nontrivial spin($S$)-dependence on the higher order anisotropy | |
| dc.type | text |