Fe(phen)(2)(NCS)(2) on Al(100): influence of AlN layer on spin crossover barrier
Fe(phen)(2)(NCS)(2) on Al(100): influence of AlN layer on spin crossover barrier
复制标题
Fe(phen)(2)(NCS)(2) on Al(100)：AlN层对自旋交叉势垒的影响
DOI：
10.1039/d1cp03782j
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发表时间：
2021
影响因子：
3.3
通讯作者：
Zhang Yachao
中科院分区：
文献类型：
--
作者：
Zhang Yachao
采用从头计算方法研究了氮化层对Fe（phen）2（NCS）2（Fephen）分子在Al（100）表面上自旋交叉（SCO）的影响.开壳层3d电子的库仑关联已被认为是使用不同的交换相关近似，包括货车德瓦尔斯密度泛函内的Hubbard-U校正。我们通过计算高自旋（HS）和低自旋（LS）状态之间的最小能量路径，通过直接约束弛豫来确定SCO能垒。结果表明，一旦沉积在Al（100）上，HS-LS能量差略有增加，因此LS态趋于稳定，通常在金属衬底上观察到。金属Al在AlN层中氧化成铝离子促进了分子吸附，同时减少了HS-LS分裂，使Fephen在其两个自旋状态之间切换。由于增强的分子-衬底键合，SCO势垒高度显著增加，这可以促进协同性。这种效果是一致的AlN促进电荷转移的界面处，从表面功函数的减少的结果。我们的研究结果揭示了表面电子结构在维持分子吸附物的自旋双稳性中起着至关重要的作用。
We study how a nitride layer affects spin crossover (SCO) in a single Fe(phen)2(NCS)2 (Fephen) molecule adsorbed on the Al(100) surface using ab initio calculations. The Coulomb correlation of the open-shell 3d electrons has been considered using a Hubbard-U correction within different exchange–correlation approximations, including the van der Waals density functional. We determine the SCO energy barrier by computing the minimum energy path between the high-spin (HS) and low-spin (LS) states via direct constraint relaxations. It is shown that the HS–LS energy difference is slightly increased once deposited on Al(100), and thus LS states tend to be stabilized, as usually observed on metallic substrates. The oxidation of metallic Al to aluminum ions in the AlN layer promotes molecular adsorption, while it decreases HS–LS splitting, making Fephen switchable between its two spin states. Due to enhanced molecule–substrate bonding, the SCO barrier height is considerably increased, which may promote cooperativity. This effect is consistent with the AlN facilitated charge transfer at the interface that results from a reduction in surface work function. Our findings reveal the crucial role that surface electronic structure plays in maintaining spin bistability of the molecular adsorbate.