Theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces
Theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces
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DOI：
10.1103/physrevmaterials.7.064409
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发表时间：
2023-02
影响因子：
3.4
通讯作者：
Anita Halder;S. Bhandary;D. O'Regan;S. Sanvito;A. Droghetti
中科院分区：
文献类型：
--
作者：
Anita Halder;S. Bhandary;D. O'Regan;S. Sanvito;A. Droghetti
我们研究了几种不同的共轭分子覆盖层对Co板磁晶各向异性（MCA）的影响，苯、环辛四烯、萘、芘和晕苯。我们根据密度泛函理论和磁力定理进行第一性原理计算。我们的研究结果表明，分子吸附倾向于有利于垂直MCA在表面。通过对各种原子分辨量的详细分析，并结合基本模型，表明其物理机制与金属-分子界面杂化有关，特别是与分子C $pz $和面外Co $dz^2}$轨道之间的化学键有关。这种效应可以从表面Co原子的轨道磁矩来估计，这是一种理论和实验都可以获得的微观观察。因此，我们提出了一种直接评估分子修饰表面的MCA修饰的方法，克服了依赖于磁化磁滞回线拟合的实验研究的局限性。最后，我们还研究了Co与C$_{60}$和Alq $_3 $这两种在有机自旋电子学中有广泛应用的分子之间的界面。我们表明，表面的修改后，这两个分子的吸附钴MCA是相似的，从而证实了最近的实验结果。
We study the modification of the magnetocrystalline anisotropy (MCA) of Co slabs induced by several different conjugated molecular overlayers, i.e., benzene, cyclooctatetraene, naphthalene, pyrene and coronene. We perform first-principles calculations based on Density Functional Theory and the magnetic force theorem. Our results indicate that molecular adsorption tends to favour a perpendicular MCA at surfaces. A detailed analysis of various atom-resolved quantities, accompanied by an elementary model, demonstrates that the underlying physical mechanism is related to the metal-molecule interfacial hybridization and, in particular, to the chemical bonding between the molecular C $p_z$ and the out-of-plane Co $d_{z^2}$ orbitals. This effect can be estimated from the orbital magnetic moment of the surface Co atoms, a microscopic observable accessible to both theory and experiments. As such, we suggest a way to directly assess the MCA modifications at molecule-decorated surfaces, overcoming the limitations of experimental studies that rely on fits of magnetization hysteresis loops. Finally, we also study the interface between Co and both C$_{60}$ and Alq$_3$, two molecules that find widespread use in organic spintronics. We show that the modification of the surface Co MCA is similar upon adsorption of these two molecules, thereby confirming the results of recent experiments.