Autieri Carmine, Cuono Giuseppe, Noce Canio, Rybak Milosz, Kotur Kamila M, Agrapidis Cliò Efthimia, Wohlfeld Krzysztof, Birowska Magdalena
International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, PL-02668 Warsaw, Poland.
Consiglio Nazionale delle Ricerche CNR-SPIN, UOS Salerno, I-84084 Fisciano, Salerno, Italy.
J Phys Chem C Nanomater Interfaces. 2022 Apr 21;126(15):6791-6802. doi: 10.1021/acs.jpcc.2c00646. Epub 2022 Apr 12.
We present a systematic study of the electronic and magnetic properties of two-dimensional ordered alloys, consisting of two representative hosts (MnPS and NiPS) of transition metal phosphorus trichalcogenides doped with 3d elements. For both hosts, our DFT + calculations are able to qualitatively reproduce the ratios and signs of all experimentally observed magnetic couplings. The relative strength of all antiferromagnetic exchange couplings, both in MnPS and in NiPS, can successfully be explained using an effective direct exchange model: it reveals that the third-neighbor exchange dominates in NiPS due to the filling of the t subshell, whereas for MnPS, the first-neighbor exchange prevails, owing to the presence of the t magnetism. On the other hand, the nearest neighbor ferromagnetic coupling in NiPS can only be explained using a more complex superexchange model and is (also) largely triggered by the absence of the t magnetism. For the doped systems, the DFT + calculations revealed that magnetic impurities do not affect the magnetic ordering observed in the pure phases, and thus, in general in these systems, ferromagnetism may not be easily induced by such a kind of elemental doping. However, unlike for the hosts, the first and second (dopant-host) exchange couplings are of similar order of magnitude. This leads to frustration in the case of antiferromagnetic coupling and may be one of the reasons of the observed lower magnetic ordering temperature of the doped systems.
我们对二维有序合金的电子和磁性进行了系统研究，该合金由过渡金属三硫属磷化物的两种代表性主体（MnPS 和 NiPS）组成，并掺杂了 3d 元素。对于这两种主体，我们的 DFT + 计算能够定性地重现所有实验观察到的磁耦合的比率和符号。在 MnPS 和 NiPS 中，所有反铁磁交换耦合的相对强度都可以使用有效的直接交换模型成功解释：结果表明，由于 t 子壳层的填充，第三近邻交换在 NiPS 中占主导地位，而对于 MnPS，由于 t 磁性的存在，第一近邻交换占主导。另一方面，NiPS 中最近邻铁磁耦合只能使用更复杂的超交换模型来解释，并且（也）很大程度上是由 t 磁性的缺失引发的。对于掺杂体系，DFT + 计算表明磁性杂质不会影响纯相中观察到的磁有序，因此，一般来说，在这些体系中，这种元素掺杂不容易诱导铁磁性。然而，与主体不同的是，第一和第二（掺杂剂 - 主体）交换耦合具有相似的量级。在反铁磁耦合的情况下，这会导致失稳，并且可能是观察到的掺杂体系磁有序温度较低的原因之一。
