We report strong ferromagnetism of quasiparticle doped holes both within the ab-plane and along the c-axis of Cu-O planes in low-dimensional Au/d-La_1.8Ba_0.2CuO₄/LaAlO₃(001) heterostructures (d = 4, 8 and 12 unit-cells) using resonant soft X-ray and magnetic scattering together with X-ray magnetic circular dichroism. Interestingly, ferromagnetism is stronger at a hole doped peak and at an upper Hubbard band of O with spin-polarization degree as high as 40%, revealing strong ferromagnetism of Mottness. For in-ab-plane spin-polarizations, the spin of doped holes in O2p–Cu3d–O2p is a triplet state yielding strong ferromagnetism. For out-of-ab-plane spin-polarization, while the spins of doped holes in both O2p–O2p and Cu3d–Cu3d are triplet states, the spin of doped holes in Cu3d–O2p is a singlet state yielding ferrimagnetism. A ferromagnetic-(002) Bragg-peak of the doped holes is observed and enhanced as a function of d revealing strong ferromagnetism coupling between Cu-O layers along the c-axis.

我们报告了准粒子掺杂空穴在低维Au/ d - La _1.8 Ba _0.2 CuO ₄ / LaAlO ₃ (001) 异质结构 ( d  = 4 , 8 和 12 个晶胞) 使用共振软 X 射线和磁散射以及 X 射线磁圆二色性。有趣的是，铁磁性在空穴掺杂峰和 O 的上哈伯德带处更强，自旋极化度高达 40%，揭示了莫特尼斯的强铁磁性。对于非平面自旋极化，O2 p –Cu3中掺杂空穴的自旋d –O2 p是产生强铁磁性的三重态。对于非平面自旋极化，虽然 O2 p -O2 p和 Cu3 d -Cu3 d中掺杂空穴的自旋是三重态，但 Cu3 d -O2 p中掺杂空穴的自旋是单重态产生亚铁磁性。观察到掺杂空穴的铁磁-（002）布拉格峰并作为d的函数增强，揭示了沿c轴的 Cu-O 层之间的强铁磁性耦合。