Colossal Temperature Coefficient of Resistivity in Epitaxial Colossal Magnetoresistive La_(0.67)Ca_(0.33)MnO_3 Films

摘要

Epitaxial La_(0.67)Ca_(0.33)MnO_3 (LCMO) films have been grown by pulsed laser deposition technique on three single crystal substrates: LaAlO_3, SrTiO_3, and NdGaO_3 having lattice mismatch with LCMO film of + 1.26%, - 0.9%, and + 0.18%. We found the transport colossal magnetoresistive (CMR) properties were improved with the reduction of a film/substrate mismatch. Processing conditions for LCMO film on NdGaO_3 substrate were optimized as well as post-annealing process was employed to achieve a superior temperature coefficient of resistivity TCR = 35%K~(-1) and the magnetoresistance MR = 66% at 7 kOe. To our knowledge, these are the record CMR parameters achieved so far.