Motivated by the recent observation of superconductivity in the pressurized trilayer Ruddlesden-Popper (RP) nickelate ${\mathrm{La}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$, we explore its structural, electronic, and magnetic properties as a function of hydrostatic pressure from first-principles calculations. We find that an orthorhombic (monoclinic)-to-tetragonal transition under pressure takes place concomitantly with the onset of superconductivity. The electronic structure of ${\mathrm{La}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ can be understood using a molecular trimer basis wherein $n$ molecular subbands arise as the $d_{z^2}$ orbitals hybridize strongly along the $c$ axis within the trilayer. The magnetic tendencies indicate that the ground state at ambient pressure is formed by nonmagnetic inner planes and stripe-ordered outer planes that are antiferromagnetically coupled along the $c$ axis, resulting in an unusual $\uparrow$, 0, $\downarrow$ stacking that is consistent with the spin density wave model previously suggested by neutron diffraction. Such a state is destabilized at the pressure where superconductivity arises. Despite the presence of $d_{z^2}$ states at the Fermi level, the $d_{x^2-y^2}$ orbitals also play a key role in the electronic structure of ${\mathrm{La}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$. This active role of the $d_{x^2-y^2}$ states in the low-energy physics of the trilayer RP nickelate, together with the distinct electronic behavior of the inner and outer planes, resembles the physics of multilayer cuprates.

中文翻译：

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压力下三层 La4Ni3O10 的电子结构和磁倾向：结构转变、分子轨道和层分化

受到最近对加压三层 Ruddlesden-Popper (RP) 镍酸盐超导性观察的启发${拉}_4{你}_3{\mathrm{氧}}_{10}$，我们通过第一性原理计算探索了其结构、电子和磁性特性作为静水压力的函数。我们发现，在压力下，斜方晶系（单斜晶系）到四方晶系的转变与超导性的开始同时发生。的电子结构${拉}_4{你}_3{\mathrm{氧}}_{10}$可以使用分子三聚体基础来理解，其中$n$分子子带出现作为$d_{z^2}$轨道沿强烈杂化$C$三层内的轴。磁倾向表明，环境压力下的基态是由非磁性内平面和条带有序外平面形成的，它们沿反铁磁耦合。$C$轴，导致不寻常的$\uparrow$, 0,$\downarrow$堆叠与先前中子衍射提出的自旋密度波模型一致。这种状态在产生超导性的压力下会不稳定。尽管存在$d_{z^2}$在费米能级上，$d_{X^2-y^2}$轨道在电子结构中也起着关键作用${拉}_4{你}_3{\mathrm{氧}}_{10}$。这种积极的作用$d_{X^2-y^2}$三层 RP 镍酸盐的低能物理状态，以及内外平面的独特电子行为，类似于多层铜酸盐的物理现象。