Lunghi Alessandro, Sanvito Stefano
School of Physics, CRANN Institute and AMBER, Trinity College, Dublin 2, Ireland.
J Chem Phys. 2020 Nov 7;153(17):174113. doi: 10.1063/5.0017118.
We present a first-principles investigation of spin-phonon relaxation in a molecular crystal of Co single-ion magnets. Our study combines electronic structure calculations with machine-learning force fields and unravels the nature of both the Orbach and the Raman relaxation channels in terms of atomistic processes. We find that although both mechanisms are mediated by the excited spin states, the low temperature spin dynamics is dominated by phonons in the THz energy range, which partially suppress the benefit of having a large magnetic anisotropy. This study also determines the importance of intra-molecular motions for both the relaxation mechanisms and paves the way to the rational design of a new generation of single-ion magnets with tailored spin-phonon coupling.
我们展示了对钴单离子磁体分子晶体中自旋 - 声子弛豫的第一性原理研究。我们的研究将电子结构计算与机器学习力场相结合，并从原子过程的角度揭示了奥尔巴赫（Orbach）弛豫通道和拉曼（Raman）弛豫通道的本质。我们发现，尽管这两种机制均由激发的自旋态介导，但低温自旋动力学由太赫兹能量范围内的声子主导，这部分抑制了具有大磁各向异性的优势。该研究还确定了分子内运动对两种弛豫机制的重要性，并为合理设计具有定制自旋 - 声子耦合的新一代单离子磁体铺平了道路。
