Effect of pseudomorphic stress on structure and transport properties of ultrathin GdBa2Cu3O7 films on (001) SrTiO3 and NdGaO3

We investigated the structure and transport properties of GdBa2Cu3O7 films on SrTiO3(001) and NdGaO3(001). We found that the films can be grown pseudomorphically up to at least 42 nm thickness on SrTiO3 whereas the critical thickness is less than 14 nm for films on NdGaO3. The carrier density of pseudomorphic films on SrTiO3 is tuned by the pseudomorphic stress field and films on SrTiO3 show higher T-* and lower T-c compared to films of the same thickness on NdGaO3. For a 28 nm thick GdBa2Cu3O7 film on SrTiO3, the hole density per CuO2 plane is reduced to 0.12, compared to 0.16 for the optimally doped and stress-free RBa2Cu3O7. The measured temperature dependence of J(c) can be understood and described by interface stress pinning. (C) 2002 American Institute of Physics.