非弹性中子散射在稀土钙钛矿研究中的应用

Investigation of the spin dynamics in dare-earth perovskites by inelastic neutron scattering

中子散射技术在科学研究中应用的重要性、独特性源自于中子本身的一些基本物理特点:带自旋、不带电荷、与原子核直接发生强相互作用、恰当的质量使其色散关系与一般物质内部的原子振动和磁性振动的元激发相当,以及可用于无损探测的强穿透性等。这些特点决定了中子散射探测技术在科学研究中无可替代的重要地位。经过多年发展,中子散射技术已经成为研究凝聚态物理中材料晶体结构以及磁结构的主要手段。此外由于中子的能量与物质中的元激发,如声子,磁振子等能量相当,中子散射也是研究物质动力学性质不可替代的关键技术。对于磁性材料来说,非弹性中子散射不仅可以研究对称性破缺下磁有序相的自旋波激发,而且可以直接探测无对称性破缺情况下的自旋关联。这对于研究磁阻挫等量子磁体中新奇的量子化自旋激发尤其重要。文章将主要介绍两种常用的非弹性散射谱仪,并结合最近在稀土钙钛矿结构体系中的具体应用,尤其是低维稀土自旋链中的分数化自旋子的激发,重点介绍非弹性散射技术的特色。

Due to the basic properties of neutrons,which carry zero charge but have nonzero magnetic moments,neutron scattering technology has become very important in condensed matter and material science.The zero charge allows neutrons to penetrate deeply into the sample,while the energies available at neutron scattering facilities are close to many excitation energy ranges in solids,corresponding to phonons in crystals,spin waves in ordered magnets,and so forth.In addition,magnetic neutron scattering shows significant differences in the spin liquid ground states where translational symmetry is not broken.These make neutron scattering well suited and unique for the study of magnetic order and spin-spin correlations,especially for the study of low dimensional and strongly frustrated quantum magnets.Here we will give a general introduction to inelastic neutron scattering.Recent research on the exotic spin excitations observed in rare-earth perovskites using inelastic neutron scattering will be discussed as well.