NMR study of the impurity-induced magnetism in the spin-Peierls system

为了阐明CuGeO 3中杂质诱导磁有序的机制，我们测量了（Cu-Mg）GeO 3和Cu（Ge-Si）O3体系中Cu的核磁共振（NMR）和核四极共振（NQR）.在（Cu-Mg）GeO_3中，我们发现NMR和NQR谱显示了精细结构，这是由于存在几个具有不同局部结构和/或磁环境的Cu位。在Cu（Ge-Si）O_3中，我们成功地测定了杂质Si原子附近的Cu原子的有序磁矩的大小。该磁矩仅为Cu ~（2+）离子的1玻尔磁子全磁矩的1.5%，这有力地表明掺杂CuGeO_3系统中的磁矩在杂质原子附近不是感生的。

In order to elucidate the mechanism for the impurity-induced magnetic ordering in the spin-Peierls compound CuGeO3, we measured nuclear magnetic resonance (NMR) and nuclear quadrupole resonances (NQR) of Cu in the (Cu-Mg)GeO3 and Cu(Ge-Si)O3 systems. In (Cu-Mg)GeO3, we found that NMR and NQR spectra show fine structure due to the presence of several Cu sites which have distinct local structural and/ magnetic environment. In Cu(Ge-Si)O3, we succeeded in determining the size of the ordered magnetic moment of the Cu atom next to the impurity Si atom. The moment is only 1.5 % of the full moment of 1 Bohr magneton of the Cu2+ ion, which strongly suggests that the magnetic moments in the doped CuGeO3 system are not induced near to the impurity atoms.