Doll Andrin, Xu Zhewen, Romankov Vladyslav, Boero Giovanni, Rusponi Stefano, Brune Harald, Salman Zaher, Dreiser Jan
PSI Center for Photon Sciences CPS, Villigen PSI, Switzerland.
PSI Center for Neutron and Muon Sciences CNM, Villigen PSI, Switzerland.
Nat Commun. 2024 Nov 28;15(1):10313. doi: 10.1038/s41467-024-54586-3.
Element-specific magnetism accessible by synchrotron-based X-ray spectroscopy has proven to be valuable to study spin and orbital moments of transition metals and lanthanides in technologically relevant thin-film and monolayer samples. The access to coherent spin superposition states relevant for emergent quantum technologies remains, however, elusive with ordinary X-ray spectroscopy. Here, we approach the study of such quantum-coherent states via the X-ray detection of microwave-driven electron paramagnetic resonance, which involves much smaller signal levels than X-ray detected ferromagnetic resonance on classical magnets. We demonstrate the feasibility of this approach with thin films of phthalocyanine-based metal complexes containing copper or vanadium centers. We also identify X-ray specific phenomena that we relate to charge trapping of secondary electrons resulting from the decay of the X-ray excited core-hole state. Our findings pave the way toward the element-specific X-ray detection of coherent superposition states in monolayers of atomic and molecular spins on virtually arbitrary surfaces.
基于同步加速器的X射线光谱可获取的元素特异性磁性，已被证明对于研究技术相关薄膜和单层样品中过渡金属和镧系元素的自旋和轨道矩非常有价值。然而，对于新兴量子技术相关的相干自旋叠加态，普通X射线光谱仍难以实现探测。在此，我们通过对微波驱动的电子顺磁共振进行X射线检测来研究此类量子相干态，与经典磁体上X射线检测的铁磁共振相比，其涉及的信号水平要小得多。我们用含有铜或钒中心的酞菁基金属配合物薄膜证明了这种方法的可行性。我们还识别出了一些X射线特定现象，这些现象与X射线激发的芯孔态衰变产生的二次电子的电荷俘获有关。我们的研究结果为在几乎任意表面上的原子和分子自旋单层中对相干叠加态进行元素特异性X射线检测铺平了道路。
