Title: Magnetic structure and electronic properties of mixed-metal Ruddlesden-Popper oxide LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$ Show Chinese title

Title: 混合金属Ruddlesden-Popper氧化物LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$的磁结构和电子性质

Abstract: Atomic, electronic, and magnetic structure of LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$ mixed-metal Ruddlesden-Popper oxide is investigated theoretically using self-consistent ACBN0 DFT + $U$ approach. We show that the electronic and magnetic properties strongly depend on the distribution of transition-metal and La/Sr ions in the lattice. Fe-Fe exchange is found to be antiferromagnetic, whereas Co-Co and Fe-Co exchange is ferromagnetic. We find that Co spin states depend on the distribution in both La/Sr and transition-metal ions. The most energetically favorable configuration is ferromagnetic, whereas the majority of metastable configurations are antiferromagnetic. LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$ was synthesized using spray-pyrolysis method. Magnetization measurements revealed antiferromgnetic behavior, thus indicating presence of metastable configurations in the synthesized material. In addition, we show that in complex systems, such as mixed-metal Ruddlesden-Popper phases, Hubbard $U$ values have to be determined for each crystallographically non-equivalent site. Show Chinese abstract

Abstract: 原子、电子和磁性结构的LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$混合金属Ruddlesden-Popper氧化物通过自洽的ACBN0 DFT +$U$方法进行了理论研究。 我们表明，电子和磁性性质强烈依赖于过渡金属和La/Sr离子在晶格中的分布。 发现Fe-Fe交换是反铁磁性的，而Co-Co和Fe-Co交换是铁磁性的。 我们发现Co的自旋状态取决于La/Sr和过渡金属离子的分布。 最能量有利的配置是铁磁性的，而大多数亚稳态配置是反铁磁性的。 LaSrCo$_{1/2}$Fe$_{1/2}$O$_4$通过喷雾热解法合成。 磁化测量显示了反铁磁行为，从而表明合成材料中存在亚稳态配置。 此外，我们还表明，在复杂系统中，如混合金属 Ruddlesden-Popper 相，必须为每个晶体学不等效位点确定 Hubbard $U$值。