论文标题
$ j_ {1} -j_ {2} $的旋转peierls过渡和带有铁磁$ j_ {1} $的扩展型号。sublattice dimerization和sigzag链的热力学，$β$ -TEVO $ _ {4} $
Spin Peierls transition of $J_{1}-J_{2}$ and extended models with ferromagnetic $J_{1}$.Sublattice dimerization and thermodynamics of zigzag chains in $β$-TeVO$_{4}$
论文作者
论文摘要
旋转$ -1/2 $链条带有铁磁交换的链条$ J_1 <0 $在第一邻居和反铁磁之间的$ J_2> 0 $之间，第二个邻居之间的$ J_2> 0 $支持两个旋转式PEIERLS（SP）的不稳定，具体取决于挫败感$α= J_2/\ Vert J_1 \ Vert J_1 \ vert $。 $ j_1-j_2 $型号的$α> 0.65 $和线性旋转phonon耦合而不是使用两个单位单元的旋转链二聚化，而是无条件地不稳定，而不是每单位电池四个旋转的旋转二聚体。向左右向邻居向邻居提供不平等的$ J_1 $，将模型扩展到$ t_ {sp} $的条件SP转换到二聚体的sublattices和较弱的特定热量$ c（t）$异常。旋转易感性$χ（t）$和$ c（t）$是通过热力学限制获得的，它通过与$α> 0.65 $和密度矩阵重新归一化组（DMRG）计算系统计算的小型系统的精确对角线化结合，高达$ n \ sim 100 $ spins的系统计算。 $ j_1-j_2 $和$γ> 0 $模型帐户在$β$ -TEVO $ -TEVO $ _ {4} $的$χ（t）$和$ C（t）$和$ c（t）$中，对于$ t> 8 $ k，但较低的$ t $表示是$ j_1-j_2 $模型的间隙。相同的参数和$ t_ {sp} = 4.6 $ k会生成$ c（t）/t $异常，它以$ 4.6 $ k的转变为$β$ -Tevo $ _ {4} $，但不是$β$ -Tevo $ _ {4} $，但不是弱$χ（t）$ signation。
The spin$-1/2$ chain with ferromagnetic exchange $J_1 < 0$ between first neighbors and antiferromagnetic $J_2 > 0$ between second neighbors supports two spin-Peierls (SP) instabilities depending on the frustration $α= J_2/\vert J_1\vert$. Instead of chain dimerization with two spins per unit cell, $J_1-J_2$ models with $α> 0.65$ and linear spin-phonon coupling are unconditionally unstable to sublattice dimerization with four spins per unit cell. Unequal $J_1$ to neighbors to the right and left extends the model to gapped ($γ> 0$) chains with conditional SP transitions at $T_{SP}$ to dimerized sublattices and a weaker specific heat $C(T)$ anomaly. The spin susceptibility $χ(T)$ and $C(T)$ are obtained in the thermodynamic limit by a combination of exact diagonalization of small systems with $α> 0.65$ and density matrix renormalization group (DMRG) calculations of systems up to $N \sim 100$ spins. Both $J_1-J_2$ and $γ> 0$ models account quantitatively for $χ(T)$ and $C(T)$ in the paramagnetic phase of $β$-TeVO$_{4}$ for $T > 8$ K, but lower $T$ indicates a gapped chain instead of a $J_1-J_2$ model as previously thought. The same parameters and $T_{SP} = 4.6$ K generate a $C(T)/T$ anomaly that reproduces the anomaly at the $4.6$ K transition of $β$-TeVO$_{4}$, but not the weak $χ(T)$ signature.
