Mass renormalization in the bandwidth-controlled Mott-Hubbard systems ${\text{SrVO}}_3$ and ${\text{CaVO}}_3$ studied by angle-resolved photoemission spectroscopy

${\text{Ca}}_{1-x}{\text{Sr}}_x{\text{VO}}_3$ is a Mott-Hubbard-type correlated electron system whose bandwidth can be varied by the V-O-V bond angle but the actual effect of bandwidth control on the electronic structure has been controversial in previous photoemission experiments. In this work, band dispersions and Fermi surfaces of ${\text{SrVO}}_3$ and ${\text{CaVO}}_3$ are studied by angle-resolved photoemission spectroscopy. Near the Fermi level $\left(E_F\right)$, three bands forming cylindrical Fermi surfaces derived from the three $\text{V}3d$ $t_{2g}$ orbitals have been observed. The observed bandwidths for both compounds are almost half of those predicted by local-density approximation band-structure calculation, confirming mass renormalization caused by electron correlation. It has been clearly demonstrated that the width of the $d$ band in ${\text{CaVO}}_3$ is narrower than that in ${\text{SrVO}}_3$, qualitatively consistent with the result of band-structure calculation. Roles of the orthorhombic lattice distortion and electron correlation in the observed band narrowing are discussed.

Figure 1

(Color online) ARPES spectra of ${\text{SrVO}}_3$ and ${\text{CaVO}}_3$ along the $k_y$ direction with $k_x=0$ in the first Brillouin zone. [(a) and (b)] Intensity plot of ${\text{SrVO}}_3$ and ${\text{CaVO}}_3$ in the $E\text{−}{k}_y$ plane. [(c) and (d)] Corresponding EDCs. The dispersive feature within $\sim 0.7\text{eV}$ of $E_F$ is the coherent part while the broad feature centered around 1.3–1.5 eV below $E_F$ is the incoherent part.

Figure 2

(Color online) Spectral weight mapping at $E_F$ for (a) ${\text{SrVO}}_3$ and (b) ${\text{CaVO}}_3$ using $h\nu =80\text{eV}$. Spectral weight has been integrated within 20 meV of $E_F$. Note that the mapping is a projection on the $k_x\text{−}{k}_y$ plane. [(c) and (d)] Fermi-surface cross sections by the $k_z=0$ plane (red curves) predicted by band-structure calculation (Ref. 15). For ${\text{CaVO}}_3$, Fermi-surface cross sections by the $k_y=0$ and $k_x=0$ planes and folded Fermi surfaces due to the orthorhombic distortion are indicated by overlapping blue solid and dashed curves, respectively.

Figure 3

(Color online) ARPES spectra of ${\text{SrVO}}_3$ in the $E\text{−}{k}_y$ plane for various photon energies corresponding to various $k_z$’s. (a1)–(a8): photon-energy dependence of the ARPES spectra near the normal emission. Insets are band dispersions for corresponding cuts predicted by band-structure calculation (Ref. 15). (b) Normal emission spectra. (c) Intensity at $E_F$ mapped in the $k_y\text{−}{k}_z$ plane. Fermi surfaces predicted by band-structure calculation (Ref. 15) are shown by blue curves. Black dotted curves indicate the $d_{yz}$ Fermi surfaces from secondary cones.

Figure 4

(Color online) ARPES spectra of ${\text{CaVO}}_3$ for various photon energies corresponding to various $k_z$’s. (a1)–(a7): photon-energy dependence of the ARPES spectra around the normal emission. Insets are band dispersions for corresponding cuts predicted by band-structure calculation (Ref. 15). (b) Normal emission spectra. (c) Intensity at $E_F$ mapped in $k_y\text{−}{k}_z$ space. Fermi surfaces predicted by band-structure calculation (Ref. 15) are shown by blue curves. Black dotted lines indicate $d_{yz}$ Fermi surfaces from secondary cones.

Figure 5

(Color online) Comparison of band dispersions in ${\text{SrVO}}_3$ and ${\text{CaVO}}_3$. ARPES spectra of (a) ${\text{SrVO}}_3$ and (b) ${\text{CaVO}}_3$ along the $\Gamma \text{-X}$ lines. The observed band is the $d_{xy}$ band. (c) Quasiparticle dispersions determined by the MDC peak positions.