Local spin anisotropy effects upon the magnetization and specific heat of dimer single molecule magnets
| dc.creator | Efremov, Dmitri V. | |
| dc.creator | Klemm, Richard A. | |
| dc.date | 2004-09-07 | |
| dc.date | 2005-09-12 | |
| dc.date.accessioned | 2026-07-07T06:30:59Z | |
| dc.date.available | 2026-07-07T06:30:59Z | |
| dc.description | We present an exactly solvable model of equal spin $s_1$ dimer single molecule magnets. The spins within each dimer interact via the Heisenberg and the most general quadratic global and local (single-ion) anisotropic spin interactions, and with the magnetic induction ${\bf B}$. For antiferromagnetic couplings and $s_1>1/2$, the low temperature $T$ magnetization ${\bm M}({\bm B})$ exhibits $2s_1$ steps of universal height and midpoint slope, the $s$th step of which occurs at the non-universal level-crossing magnetic induction $B_{s,s_1}^{\rm lc}(θ,ϕ)$, where $θ,ϕ$ define the direction of ${\bm B}$. The specific heat $C_V$ exhibits zeroes as $T\to0$ at these $B_{s,s_1}^{\rm lc}(θ,ϕ)$ values, which are equally surrounded by universal peak pairs as $T\to0$. The non-universal $B_{s,s_1}^{\rm lc}(θ,ϕ)$ values lead to a rich variety of magnetization plateau behavior, the structure and anisotropy of which depend upon the various global and local anisotropic spin interaction energies. We solve the model exactly for $s_1=1/2$, 1, and 5/2, and present ${\bm M}({\bm B})$ and $C_V({\bm B})$ curves at low $T$ for these cases. For weakly anisotropic dimers, rather simple analytic formulas for ${\bm M}({\bm B})$ and $C_V({\bm B})$ at arbitrary $s_1$ accurately fit the exact solutions at sufficiently low $T$ or large $B$. An expression for $B_{s,s_1}^{\rm lc}(θ,ϕ)$ accurate to second order in the four independent anisotropy energies is derived. Our results are discussed with regard to existing experiments on $s_1=5/2$ Fe$_2$ dimers, suggesting further experiments on single crystals of these and some $s_1=9/2$ Mn$_4$]$_2$ dimers are warranted. | |
| dc.description | 22 pages, 26 figures, submitted to PRR | |
| dc.identifier | https://arxiv.org/abs/cond-mat/0409168 | |
| dc.identifier | http://arxiv.org/abs/cond-mat/0409168 | |
| dc.identifier | Phys. Rev. B {\bf 74} (6), 064408 (2006). | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/98486 | |
| dc.subject | Mesoscale and Nanoscale Physics | |
| dc.subject | Statistical Mechanics | |
| dc.title | Local spin anisotropy effects upon the magnetization and specific heat of dimer single molecule magnets | |
| dc.type | text |