$\mathrm{CrN}/\mathrm{MgO}(111)$ multilayers modeled via ab initio calculations give rise to nanoscale, scalable, spatially separated two-dimensional electron and hole gases, each confined to its own CrN interface. Because of the Cr $3d^3$ configuration, both electron and hole gases are based on correlated transition-metal layers involving bands of $3d$ character. Transport calculations predict each subsystem will have a large thermopower, on the order of $250\mu \mathrm{V}/\mathrm{K}$ at room temperature. These heterostructures combine a large thermoelectric efficiency with scalable nanoscale conducting sheets; for example, operating at a temperature difference of 50 K, 40 bilayers could produce a 1-V voltage with a film thickness of 100 nm.

• Thermoelectric effects
• Multilayer thin films
• Nitrides
• Oxides
• Thermoelectrics
• Two-dimensional electron gas