Correlating polar distortions and interfacial charge at the polar/non-polar LaCrO3/SrTiO3 (001) interface*

The relationship between the sheet carrier concentration, ns, of LaCrO3(LCO)/SrTiO3(STO) heterostructures and their structure has been investigated. Under low oxygen partial pressure, the STO substrate is reduced during growth as evidenced by a high ns of 10¹⁶ cm⁻². By controlling the post-growth annealing conditions, heterostructures with ns of 10¹³–10¹⁶ cm⁻² are achieved. The atomic-scale structure of the samples is obtained using high-resolution synchrotron x-ray diffraction measurements. For heterostructures with ns at or below 3 × 10¹³ cm⁻², polar distortions are present within the LCO layers and increase in magnitude with a decrease in sheet carrier concentration. These distortions are absent for samples with ns on the order of 10¹⁵–10¹⁶ cm⁻² where interfacial carriers play a role in alleviating the polar discontinuity at the LCO/STO interface. These results suggest that interfacial charge carriers and polar distortions can act as complementary mechanisms to alleviate the polar discontinuity at polar/non-polar complex oxide interfaces.