Controlling Mott insulator states has been a long-standing topic in condensed matter physics. Among various controlling parameters, two-dimensional (2D) confinement in epitaxial heterostructures has been demonstrated to convert the correlated metallic nature of ${\mathrm{SrVO}}_3$ into a Mott insulator by reducing the quantum well thickness. Here, we fabricate double quantum well (DQW) structures of ${\mathrm{SrVO}}_3$ with a magnetic barrier of ${\mathrm{EuTiO}}_3$ to tune the hybridization of wave functions by a magnetic field. A significant positive magnetoconductance is observed for DQWs with barriers thinner than 2 nm, while DQWs with thicker barriers do not show such large positive magnetoconductance, instead behaving as a parallel circuit of two single QWs. The observed positive magnetoconductance is accounted for in terms of enhanced hybridization of V $3d$ orbitals across the ${\mathrm{EuTiO}}_3$ barrier under a magnetic field, where the barrier height is reduced by the Zeeman splitting of Ti $3d$ bands in forced ferromagnetic ordering of localized $4f$ electrons on $\mathrm{E}{\mathrm{u}}^{2+}$ sites.

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• Magnetotransport
• Mott insulators
• Oxides
• Quantum wells
• Thin films
• Molecular beam epitaxy