论文标题
单分子磁铁中缓慢磁性松弛的起源
Origins of Slow Magnetic Relaxation in Single-Molecule Magnets
论文作者
论文摘要
指数和功率定律温度依赖性被广泛用于拟合单分子磁体中磁性松弛时间的实验数据。我们得出了一种理论，以表明这些规则是如何源于底底放松机制并阐明其发生条件的。该理论解决了最近实验中发现的比预期低于预期的Orbach屏障的难题，并阐明了由于伪装的拉曼过程而阐明了它。我们的结果强调了降低基态双重底线之间直接隧穿的速率，以实现磁分子中的长时间连贯性。为此，大型自旋和小的横向磁各向异性可以减少过渡算子的幅度，而刚性配体可能会削弱自旋光子耦合，因为它们会增加振动模式的能量，并更好地屏幕声音子。
Exponential and power law temperature dependences are widely used to fit experimental data of magnetic relaxation time in single molecular magnets. We derived a theory to show how these rules arise from the underling relaxation mechanisms and to clarify the conditions for their occurrence. The theory solves the puzzle of lower-than-expected Orbach barriers found in recent experiments, and elucidates it as a result of the Raman process in disguise. Our results highlight the importance of reducing the rate of direct tunneling between the ground state doublet so as to achieve long time coherence in magnetic molecules. To this end, large spin and small transverse magnetic anisotropy can reduce magnitude of the transition operator, and rigid ligands may weaken the spin-phonon coupling in that they raise the energy of vibrational modes and better screen the acoustic phonons.
