论文标题
建模自旋旋转过渡 - $ 1/2 $与相关状态的链条：$ j_1-j_2 $型号，cugeo $ _3 $和ttf-cus $ _4 $ c $ c $ _4 $（cf $ _3 $）$ _ 4 $ _ 4 $
Modeling the spin-Peierls transition of spin-$1/2$ chains with correlated states: $J_1-J_2$ model, CuGeO$_3$ and TTF-CuS$_4$C$_4$(CF$_3$)$_4$
论文作者
论文摘要
以$ t_ {sp} $ spin- $ 1/2 $链的旋转peierls过渡与各向同性交易所相互作用已建模为$ t> t> t> t> t_ {sp} $的相关性，而平均字段则为$ t <t_t_ {sp {sp} $相关。我们在$ J_1-J_2 $模型中使用反铁磁性交换$ J_1 $和$ J_2 =αj_1$在第一和第二个邻居之间，以及可变的挫败感$ 0 \leqα\ leq 0.50 $之间。通过短链的对角度确切的对角和低$ t $的对角度，密度矩阵重质化组计算逐渐更长的链条，以高$ t $的对角度达到热力学极限。与平均场结果相反，具有线性自旋式耦合和谐波绝热晶格的1D模型的相关状态提供了一个内部一致的描述，其中参数$ t_ {sp} $可以使刚度和晶状体二聚体二聚体$Δ（t）$产生。 $ t_ {sp} $和$δ（δ，α）$，$ t = 0 $差距引起的$ t = 0 $差异之间的关系在很大程度上取决于$α$，并且与无关的旋转链中的BCS间隙关系偏离了BCS间隙关系。相关状态帐户数量地说明TTF-CUS $ _4 $ C $ _4 $（cf $ _3 $）$ _ 4 $ crystals（$ j_1 = 79 $ k，$α= 0 $，$ t_ {sp} = 12 $ k）和cugeo $ _3 $ _3 $ j_1 = 160 = 160 = 160 = 160 = 160 = 160 = 160 = 160 = 160 = 160 = 160 = 0.3 $ t_ {sp} = 14 $ k）。相同的参数描述了Cugeo $ _3 $和非弹性中子散射的特定热异常。用相关状态建模自旋peierls过渡，利用了一个事实，即$δ（0）$将自旋相关范围限制为$ t = 0 $，而$ t> 0 $将范围限制为$δ= 0 $。
The spin-Peierls transition at $T_{SP}$ of spin-$1/2$ chains with isotropic exchange interactions has previously been modeled as correlated for $T > T_{SP}$ and mean field for $T < T_{SP}$. We use correlated states throughout in the $J_1-J_2$ model with antiferromagnetic exchange $J_1$ and $J_2 = αJ_1$ between first and second neighbors, respectively, and variable frustration $0 \leq α\leq 0.50$. The thermodynamic limit is reached at high $T$ by exact diagonalization of short chains and at low $T$ by density matrix renormalization group calculations of progressively longer chains. In contrast to mean field results, correlated states of 1D models with linear spin-phonon coupling and a harmonic adiabatic lattice provide an internally consistent description in which the parameter $T_{SP}$ yields both the stiffness and the lattice dimerization $δ(T)$. The relation between $T_{SP}$ and $Δ(δ,α)$, the $T = 0$ gap induced by dimerization, depends strongly on $α$ and deviates from the BCS gap relation that holds in uncorrelated spin chains. Correlated states account quantitatively for the magnetic susceptibility of TTF-CuS$_4$C$_4$(CF$_3$)$_4$ crystals ($J_1 = 79$ K, $α= 0$, $T_{SP} = 12$ K) and CuGeO$_3$ crystals ($J_1 = 160$ K, $α= 0.35$, $T_{SP} = 14$ K). The same parameters describe the specific heat anomaly of CuGeO$_3$ and inelastic neutron scattering. Modeling the spin-Peierls transition with correlated states exploits the fact that $δ(0)$ limits the range of spin correlations at $T = 0$ while $T > 0$ limits the range at $δ= 0$.
