Windsor Y W, Lee S-E, Zahn D, Borisov V, Thonig D, Kliemt K, Ernst A, Schüßler-Langeheine C, Pontius N, Staub U, Krellner C, Vyalikh D V, Eriksson O, Rettig L
Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Berlin, Germany.
Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
Nat Mater. 2022 May;21(5):514-517. doi: 10.1038/s41563-022-01206-4. Epub 2022 Feb 24.
Ultrafast manipulation of magnetism bears great potential for future information technologies. While demagnetization in ferromagnets is governed by the dissipation of angular momentum, materials with multiple spin sublattices, for example antiferromagnets, can allow direct angular momentum transfer between opposing spins, promising faster functionality. In lanthanides, 4f magnetic exchange is mediated indirectly through the conduction electrons (the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction), and the effect of such conditions on direct spin transfer processes is largely unexplored. Here, we investigate ultrafast magnetization dynamics in 4f antiferromagnets and systematically vary the 4f occupation, thereby altering the magnitude of the RKKY coupling energy. By combining time-resolved soft X-ray diffraction with ab initio calculations, we find that the rate of direct transfer between opposing moments is directly determined by this coupling. Given the high sensitivity of RKKY to the conduction electrons, our results offer a useful approach for fine tuning the speed of magnetic devices.
超快磁操控对未来信息技术具有巨大潜力。虽然铁磁体中的退磁由角动量耗散控制，但具有多个自旋子晶格的材料，例如反铁磁体，可以允许相反自旋之间的直接角动量转移，有望实现更快的功能。在镧系元素中，4f磁交换通过传导电子间接介导（Ruderman-Kittel-Kasuya-Yosida（RKKY）相互作用），而这种条件对直接自旋转移过程的影响在很大程度上尚未得到探索。在这里，我们研究了4f反铁磁体中的超快磁化动力学，并系统地改变4f占据情况，从而改变RKKY耦合能的大小。通过将时间分辨软X射线衍射与从头算相结合，我们发现相反磁矩之间的直接转移速率直接由这种耦合决定。鉴于RKKY对传导电子的高敏感性，我们的结果为微调磁性器件的速度提供了一种有用的方法。
