Hyperfine structure of magnetic excitations in a Tb-based single-molecule magnet studied by high-resolution neutron spectroscopy
Hyperfine structure of magnetic excitations in a Tb-based single-molecule magnet studied by high-resolution neutron spectroscopy
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高分辨率中子能谱研究铽基单分子磁体磁激发的超精细结构
DOI：
10.1103/physrevb.88.064405
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Y. Inamura
中科院分区：
文献类型：
--
作者：
M. Kofu,* O. Yamamuro;T. Kajiwara;Y. Yoshimura;M. Nakano;K. Nakajima;S. Ohira-Kawamura;T. Kikuchi;Y. Inamura
我们报告了基于稀土的单分子磁体的非弹性中子散射结果，Tb-Cu双核配合物。利用高分辨率中子斩波光谱仪，阐明了激发的细节。在和12.3 meV下可以清楚地观察到磁激发。1.7 meV的跃迁能对应于由交流磁化率测量得到的磁弛豫能垒。这表明在1.7 meV下，磁化反转是通过简并激发态对之间的量子隧穿发生的，这被称为热激活隧穿过程。有趣的是，这些激发在能量上表现出进一步的峰值分裂，并且它们的能量与动量转移无关。我们基于自旋哈密顿量的计算表明：(i) 1.7 meV的激发源于Tband Cu之间的交换耦合，（ii） 12.3 meV的激发对应于Tbmoment多重态J之间的跃迁，（iii）能量的精细峰分裂是由于核自旋与电子自旋和轨道磁矩之间的超精细相互作用。
We report inelastic neutron scattering results on a rare-earth-based single-molecule magnet, the Tb-Cu dinuclear complex. By means of a high-resolution neutron chopper spectrometer, the details of the excitations were clarified. The magnetic excitations are clearly observed atand 12.3 meV. The transition energy of 1.7 meV corresponds to the energy barrier of magnetic relaxation estimated from an ac magnetic susceptibility measurement. This indicates that the magnetization reversal occurs through quantum tunneling between pairs of degenerated excited states at 1.7 meV, which is called a thermally activated tunneling process. Interestingly, these excitations exhibit further peak splitting in energy and their energies are independent of momentum transfer. Our calculation, which is based on a spin Hamiltonian, suggests that (i) the excitation at 1.7 meV originates from the exchange coupling between Tband Cu, (ii) the excitation at 12.3 meV corresponds to the transition between the multiplets J of the Tbmoment, and (iii) the fine peak splitting in energy is due to the hyperfine interaction between the nuclear spin and electron spin and orbital magnetic moments.