Data files relating to “Interface control by chemical and dimensional matching in an oxide heterostructure” 1_2009NZO_RHEED *.txt 2_2009NZO_RHEED_Scan_mode_image *.bmp 3_2009NZO_RHEED_LAO_Before *.bmp 4_2009NZO_RHEED_After *.bmp 5_2009NZO_XRD_2theta *.csv 6_0212LZO_XRD_2theta *.csv 7_0912SDC_RHEED_LSAT_Before *.bmp 8_0912SDC_RHEED_After *.bmp 9_0912SDC_RHEED *.txt 10_0912SDC_RHEED_Scan_mode_image *.bmp 11_0602LDC_RHEED_STO_Before *.bmp 12_0602LDC_RHEED_After *.bmp 13_0602LDC_RHEED *.txt 14_0602LDC_RHEED_Scan_mode_image *.bmp 15_3005CO_RHEED_LAO_Before *.bmp 16_3005CO_RHEED_After *.bmp 17_3005CO_RHEED *.txt 18_3005CO_RHEED_Scan_mode_image *.bmp 19_1201YSZ_RHEED *.txt 20_1201YSZ_RHEED_Scan_mode_image *.bmp 21_1201YSZ_RHEED_YAO_Before *.bmp 22_1201YSZ_RHEED_After *.bmp 23_1110LAO_AFM_raw.mi *.mi 24_1110LAO_AFM_512x512 *.csv 25_2009NZO_RHEED_LAO_Superstructure *.bmp 26_0212LZO_RHEED *.txt 27_0212LZO_RHEED_Scan_mode_image *.bmp 28_2009NZO_RC *.csv 29_2009NZO_LAO_RC *.csv 30_0212LZO_RC *.csv 31_0212LZO_LAO_RC *.csv 32_0212LZO_XRR *.csv 33_2009NZO_XRR *.csv 34_1209NZOa_AFM_512x512 *.csv 35_1209NZOa_AFM_raw *.mi 36_1004LZO_AFM_512x512 *.csv 37_1004LZO_AFM_raw.mi *.mi 38_1004LZO_RSM *.csv 39_1709NZO_RSM *.csv 40_2009NZO_Pole *.csv 41_2009NZO_LAO_Pole *.csv Methods Sample Growth All heterostructure samples were grown by pulsed laser deposition of dense ceramic targets of the source material and deposited onto single crystal perovskite substrates. The PLD system consists of a Neocera high vacuum chamber equipped with a high pressure RHEED system, including a kSA 400 analysis system and a Staib electron gun, together with a Coherent Lambda Physik COMPex Pro 248 nm KrF Excimer laser. Laser fluences of 1.82 to 2.46 J/cm2 and pulse frequencies of 1 or 2 Hz were used to deposit the thin films. The system operates with a base pressure of 2×10-8 Torr, and the deposition gas pressure is controlled using a mass flow controller with high purity O2. The substrates are heated by radiation and the temperature is monitored and controlled with a thermocouple, however the deposition temperatures reported in the main text refer to the temperature of the substrate holder measured using a pyrometer. The heterostructures were deposited at substrate temperatures ranging from 600 to 800 °C with oxygen partial pressures varied between 1 and 10 mTorr. Diffraction Phase analysis of the heterostructure samples was carried out by collecting theta/2theta scans using a PANalytical X’Pert Pro diffractometer in Bragg-Brentano geometry with monochromated Co Kalpha1 radiation (lambda = 1.78896 Å). X-ray reflectivity, rocking curves, pole figures and reciprocal space maps were measured using a 4-circle PANalytical MRD diffractometer with a Cu X-ray source. Sample thicknesses determined by simulating the X-ray reflectivity data using IMD software37 were compared with figures extracted from fitting the Pendellosung fringes observed about Bragg peaks in the theta/2theta patterns with a modified sinc function. Atomic Force Microscopy AFM images were collected using an Agilent Technologies 5400 AFM in ACAFM mode over 3micron x 3micron or 5micron x 5micron area. Images consist of 512 x 512 data point matrix.