Relations between structural distortions and transport properties in Nd0.5Ca0.5MnO3 strained thin films

Strained thin films of charge/orbital-ordered (CO/OO) Nd0.5Ca0.5MnO3 with various thicknesses have been grown on (100) SrTiO3 and (100) LaAlO3 substrates, by using the pulsed laser deposition technique. The thickness of the films drastically influences the transport properties. As the thickness decreases, the CO transition becomes more favoured while at the same time the insulator-to-metal transition temperature becomes less favoured under application of a 7?T magnetic field. Clear relationships between the structural distortions and the transport properties are established. They are explained on the basis of the elongation and the compression of the Mn-O-Mn and Mn-O bond angles and distances of the Pnma structure, which modify the bandwidth and the Jahn-Teller distortion in these materials.