We have successfully synthesized and transferred graphene (Gr) monolayers on top of epitaxial mixed valence La_0.7Sr_0.3CoO₃ (LSCO) thin films. Raman spectroscopy reveals that Jahn-Teller (JT) modes associated with the oxygen octahedral distortions usually unobserved for bare LSCO are activated by the deposited graphene. The appearance of these JT modes in the Gr/LSCO heterostructure is attributed to the electronic interactions at the interface between the graphene and the LSCO thin film promoting intermediate spin states of the Co ions. As a result, the magnetic properties of LSCO are affected. Indeed, magnetization measurements show a phase transition at ~135 K which is due to the presence of the graphene while the ferromagnetic transition of bare LSCO films is observed at~200 K. This magnetic phase is confirmed by Raman spectroscopy measurements as a function of temperature revealing a vibrational transition around the same temperature.

我们已经成功地在外延混合价La _0.7 Sr _0.3 CoO ₃上合成并转移了石墨烯（Gr）单层（LSCO）薄膜。拉曼光谱表明，与裸露的LSCO通常无法观察到的氧八面体形变相关的Jahn-Teller（JT）模式被沉积的石墨烯激活。这些JT模式在Gr / LSCO异质结构中的出现归因于石墨烯与LSCO薄膜之间界面处的电子相互作用，从而促进了Co离子的中间自旋态。结果，LSCO的磁性能受到影响。的确，磁化强度测量表明在〜135 K处存在相变，这是由于石墨烯的存在，而裸露的LSCO薄膜的铁磁跃迁则在〜200 K处观察到。该磁相通过拉曼光谱测量得到了温度的函数。揭示了在相同温度下的振动转变。