论文标题
变形旋转 - $ \ frac12 $ square晶格中的反铁磁性naznvopo $ _4 $（hpo $ _4 $）
Deformed spin-$\frac12$ square lattice in antiferromagnetic NaZnVOPO$_4$(HPO$_4$)
论文作者
论文摘要
We report the structural and magnetic properties of a new spin-$\frac12$ antiferromagnet NaZnVOPO$_4$(HPO$_4$) studied via x-ray diffraction, magnetic susceptibility, high-field magnetization, specific heat, and $^{31}$P nuclear magnetic resonance (NMR) measurements, as well as density-functional band-structure calculations.虽然该化合物的热力学特性由$ j_1-j_2 $ square-lattice模型很好地描述，但\ textit {ab intio}计算表明，旋转晶格的显着变形。从拟合到磁敏感性，我们确定了$ \ bar j_1 \ simeq -1.3 $ k和$ \ bar j_2 \ simeq 5.6 $ k的平均邻居和第二个邻居交换耦合。如果考虑到$ j_1 $中的20 \％空间各向异性，则15.3 \的实验饱和场与这些估计值一致。特定的热数据信号信号在$ t _ {\ rm n} \ simeq 2.1 $ k处的磁性长距离顺序发作，这在NMR Spin-strattice松弛率中得到了尖锐的峰值。 NMR光谱标志着两个无Q的P线的叠加，这是由于两个非QVART P站点的叠加，在该站点上，具有强大的超精细耦合和短$ T_1 $的宽线被确定为位于磁性平面内的P（1）站点，而狭窄的线路与弱的超精细耦合和较弱的$ T_1 $的狭窄线指定为P t_1 $。
We report the structural and magnetic properties of a new spin-$\frac12$ antiferromagnet NaZnVOPO$_4$(HPO$_4$) studied via x-ray diffraction, magnetic susceptibility, high-field magnetization, specific heat, and $^{31}$P nuclear magnetic resonance (NMR) measurements, as well as density-functional band-structure calculations. While thermodynamic properties of this compound are well described by the $J_1-J_2$ square-lattice model, \textit{ab initio} calculations suggest a significant deformation of the spin lattice. From fits to the magnetic susceptibility we determine the averaged nearest-neighbor and second-neighbor exchange couplings of $\bar J_1\simeq -1.3$ K and $\bar J_2\simeq 5.6$ K, respectively. Experimental saturation field of 15.3\,T is consistent with these estimates if 20\% spatial anisotropy in $J_1$ is taken into account. Specific heat data signal the onset of a magnetic long-range order at $T_{\rm N} \simeq 2.1$ K, which is further supported by a sharp peak in the NMR spin-lattice relaxation rate. The NMR spectra mark the superposition of two P lines due to two noneqivalent P sites where the broad line with the strong hyperfine coupling and short $T_1$ is identified as the P(1) site located within the magnetic planes, while the narrow line with the weak hyperfine coupling and long $T_1$ is designated as the P(2) site located between the planes.
