NMR and neutron-scattering experiments on the cuprate superconductors: A critical re-examination.
NMR and neutron-scattering experiments on the cuprate superconductors: A critical re-examination.
复制标题
DOI：
10.1103/physrevb.54.7561
复制
发表时间：
1996-01
期刊：
影响因子：
--
通讯作者：
Zha;Barzykin;Pines
中科院分区：
文献类型：
--
作者：
Zha;Barzykin;Pines
我们证明，通过利用动态自旋-自旋响应函数的 Millis-Monien-Pines 平均场唯象表达式，并重新检查用于 NMR 实验的标准 Shastry-Mila-Rice 超精细哈密顿量，可以协调 LSCO 和 YBCO 上的 NMR 和中子散射实验。 Aeppli 等人最近在 LSCO (x=14%) 上的中子散射结果与 $^{63}T_1$ 的 NMR 测量以及 Barzykin 和 Pines 提出的磁标度行为定量一致。通过在氧核与其下一个最近邻居 $Cu^{2+}$ 自旋之间引入新的转移超精细耦合 $C'$ 来实现 $^{17}T_1$ 弛豫率与中子实验中看到的自旋涨落谱中的不通约程度的协调；这导致近乎完美地消除了不相称的自旋波动峰对 LSCO 氧弛豫率的影响。新的 $C'$ 项的包含也导致了一种自然的解释，在单组分模型中，不同场方向的各向异性氧弛豫率的不同温度依赖性，最近由 Martindale $et~al$ 观察到。在 LSCO 系统中，测量到的各向异性比 $R= ^{63}T_{1ab}/^{63}T_{1c}$ 的掺杂显着降低，从 ${\rm La_2CuO_4}$ 的 $R =3.9$ 到 LSCO (x=15%) 的 $R ~ 3.0$，与中子中测量的不相称自旋涨落峰值的偏移的掺杂依赖性相兼容通过适当选择直接和转移超精细耦合常数 $A_{\beta}$ 和 B 进行实验。
We show that it is possible to reconcile NMR and neutron scattering experiments on both LSCO and YBCO, by making use of the Millis-Monien-Pines mean field phenomenological expression for the dynamic spin-spin response function, and reexamining the standard Shastry-Mila-Rice hyperfine Hamiltonian for NMR experiments. The recent neutron scattering results of Aeppli et al on LSCO (x=14%) are shown to agree quantitatively with the NMR measurements of $^{63}T_1$ and the magnetic scaling behavior proposed by Barzykin and Pines. The reconciliation of the $^{17}T_1$ relaxation rates with the degree of incommensuration in the spin fluctuation spectrum seen in neutron experiments is achieved by introducing a new transferred hyperfine coupling $C'$ between oxygen nuclei and their next nearest neighbor $Cu^{2+}$ spins; this leads to a near-perfect cancellation of the influence of the incommensurate spin fluctuation peaks on the oxygen relaxation rates of LSCO. The inclusion of the new $C'$ term also leads to a natural explanation, within the one-component model, the different temperature dependence of the anisotropic oxygen relaxation rates for different field orientations, recently observed by Martindale $et~al$. The measured significant decrease with doping of the anisotropy ratio, $R= ^{63}T_{1ab}/^{63}T_{1c}$ in LSCO system, from $R =3.9$ for ${\rm La_2CuO_4}$ to $R ~ 3.0$ for LSCO (x=15%) is made compatible with the doping dependence of the shift in the incommensurate spin fluctuation peaks measured in neutron experiments, by suitable choices of the direct and transferred hyperfine coupling constants $A_{\beta}$ and B.