Turning a Nickelate Fermi Surface into a Cupratelike One through Heterostructuring

Using the local density approximation and its combination with dynamical mean-field theory, we show that electronic correlations induce a single-sheet, cupratelike Fermi surface for hole-doped $1/1$ ${\mathrm{LaNiO}}_3/{\mathrm{LaAlO}}_3$ heterostructures, even though both $e_g$ orbitals contribute to it. The Ni $3d_{3z^2-1}$ orbital plays the role of the axial Cu $4s$-like orbital in the cuprates. These two results indicate that “orbital engineering” by means of heterostructuring should be possible. As we also find strong antiferromagnetic correlations, the low-energy electronic and spin excitations in nickelate heterostructures resemble those of high-temperature cuprate superconductors.

Figure 1

The $1/1$ ${\mathrm{LaNiO}}_3/{\mathrm{LaAlO}}_3$ heterostructure (left) and its LDA ($N\mathrm{MTO}$) band structures without (center) and with (right) strain. The Bloch vector is along the lines $\Gamma (0,0,0)-Z(0,0,\frac{\pi }{c})-R(0,\frac{\pi }{a},\frac{\pi }{c})-A(\frac{\pi }{a},\frac{\pi }{a},\frac{\pi }{c})-Z(0,0,\frac{\pi }{c})$. The shading gives the $x^2-y^2$ vs $3z^2-1e_g$ Wannier-function character.

Figure 2

Cross section of the FS with the $k_z=0$ plane for the unstrained $1/1$ heterostructure. Left: LDA. Middle: $\mathrm{LDA}+\mathrm{DMFT}$ ($U=6.7\mathrm{eV}$). Right: $\mathrm{LDA}+\mathrm{DMFT}$ $k$-integrated spectral functions (in arbitrary units) projected onto the $x^2-y^2$ (full) and $3z^2-1$ (dashed) Wannier functions.

Figure 3

Energy levels for the unstrained two-site model with $U=6.4\mathrm{eV}$ as a function of the splitting $\Delta$ between the energies of the $3z^2-1$ and $x^2-y^2$ Wannier orbitals. The LDA value of $\Delta$ is indicated by the dashed line. $O_F$ ($O_{AF}$) denotes a configuration with the same (different) orbital(s) on the two sites.