Readme for dataset relating to Correlated metal LaNiO3 as a p-type transparent conductor 


Shivang Beniwal(a,b), Emmeline G. Poole(b), Jacob Plowman(b), Troy D. Manning(b), Teresa Partida Manzanera(c), Kevin Sanderson(c), Matthew Dyer(b), Matthew J. Rosseinsky(b)*, Jonathan Alaria(a)* 

a Department of Physics, University of Liverpool, Oxford Street, L69 7ZE, UK
b Materials Innovation Factory, Department of Chemistry, University of Liverpool, 51 Oxford Street, L7 3NY, UK
c Pilkington Technology Management Ltd.,NSG Group European Technical Centre Hall Lane, Lathom Ormskirk L40 5UF, UK 

All files are human readable acsii format (.csv, .txt, .asc). AFM files are in .mi format which can be processed in the open source software Gwyddion.

Target preparation: A dense bulk target for growing LaNiO3 films was obtained from La2O3 (Sigma Aldrich, ≥ 99.99%), and NiO (Thermo Scientific, ≥ 99.99%) powders using the solid state synthesis route. For this, the powders were first mixed, ball milled, pressed into a pellet and calcined at 900 °C for 3 h in a box furnace with a heating and cooling rate 5 °C/min. The pellet was then reground to powder and ball milled and pressed into a pellet using Cold Isostatic Pressing at 30 kpsi followed by sintering at 1100 °C for 3 h, heating and cooling at 5 °C/min, resulting in a 25 mm diameter pellet of >75% relative density. Powder from the target was digested in HNO3 and HCl for Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) to confirm the 1:1 La:Ni stoichiometry.  

Thin Film Deposition: Thin films of varying thicknesses (1.5–22 nm) were deposited on single-side polished SrTiO3 (0 0 l) (Pi-KEM Ltd.) single crystal substrates using PLD on a PVD Products NanoPLD using a KrF excimer laser (Lambda Physik) with a wavelength of 248 nm, keeping the substrate to target distance fixed at 5 cm. SrTiO3 (001) single crystal substrates (10 mm x 10 mm x 0.5 mm) were prepared by sonication in an ethanol bath for 15 minutes, after which they were then dried in a nitrogen flow. Following this, they were then affixed to the PLD substrate holder plate using silver dag. The LaNiO3 target was polished each time before deposition. After loading the substrate holder plate onto the heater assembly the PLD chamber was evacuated to a base pressure of < 8×10−7 Torr, and then the substrate was heated at a rate of 30 °C/min to a nominal temperature of 650 °C in 80 mTorr of O2 for 30 minutes before deposition and these conditions maintained during and for 30 mins after the deposition. The laser was set to an output energy of 220 mJ at 3 Hz, ensuring the energy density at the target to be more than the threshold value of ~1 J/cm2. 

Structural Characterization: X-ray measurements on the LaNiO3 thin films were performed on a Rigaku Smartlab with a Cu source and a Ge (220) monochromator producing a wavelength of 1.54056 Å, accompanied by a HyPix-3000 two-dimensional semiconductor X-ray detector in parallel beam optics. The step size for the out of plane measurements was 0.01 ° with a speed duration time of 1.2 °/min. The topography of the fabricated films was analysed using a Keysight 5600LS microscope Atomic Force Microscopy (AFM) in tapping mode, and the data was analysed via the open-source software Gwyddion. Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX) mapping were performed on a Tescan S8000. Samples were mounted onto aluminium SEM stubs using conductive adhesive and secured with silver paint, with the sample edges additionally coated to ensure proper grounding. No additional conductive coating was applied prior to measurement. 

Electrical Properties: The electrical transport measurements for the films were performed in a Quantum Design Physical Properties Measurement System (PPMS), which includes a pumped helium cryostat allowing measurement of resistivity as a function of temperature down to 2.5 K. The instrument is also equipped with a superconducting magnet capable of generating magnetic fields of up to 14 T, which was used to extract the Hall resistance from −14 T to 14 T. The antisymmetric part of the measured resistivity was then calculated. The contacts on the films were made using Au wires in Van der Pauw geometry. 

Optical Properties: Ellipsometry data were measured with a J.A. Woollam M2000UI variable angle spectroscopic ellipsometer with a wavelength range of 240–1700 nm. The measurements were taken around the Brewster angle θB at three different angles of 65, 70, and 75°, and the obtained raw data was modelled using “CompleteEASE” software.