类型 关键词 频次 2 别名 crystal field splitting 相关论文 Orbital Signatures of Density Wave Transition in La3Ni2O7-delta and La2PrNi2O7-delta RP-Nickelates Probed via in-situ X-ray Absorption Near-edge Spectroscopy Electronic correlations and Hund’s rule coupling in trilayer nickelate La4Ni3O10