مشخصات پژوهش

The impact of pulse repetition rate and film thickness on the magnetic, magnetoresistance (MR) and anisotropic magnetoresistance (AMR) has been investigated for La0.4Pr0.3Ca0.3MnO3 thin films grown on LaAlO3 (LAO) substrates by pulsed laser deposition technique. Change in repetition rate led to a difference in growth modes and altered the magnetic and electrical properties (MR and AMR) of thin films. The XRD results show that in the films with the thickness of 100 nm, by increasing the pulse repetition rate from 2 to 7 Hz the strain level doesn’t change, while strain significantly increased at the repetition rate of 10Hz. Analysis of transport and magnetization measurements show that at 2 and 5 Hz deposited films, the ferromagnetic metallic behavior is dominant, while in the film deposited at 10 Hz the antiferromagnetic (AFM) insulating phase increased. Moreover, with increasing strain in the thinner films (40 nm), deposited at 2 Hz, AFM phase is strengthened. Exchange bias confirms the existence of a dead layer in 100 nm film deposited at 10 Hz and 40 nm film deposited at 2 Hz. In addition, high strain in thinner films led to an enhanced Jahn-Teller coupling, so the angular momentum and spin-orbital/lattice interactions are significantly increased, which led to a lower magnetoresistance in thinner films. These results suggest that the pulse repetition rate provides an additional degree of freedom to tune magnetic and electrical properties of manganite thin films prepared by pulsed laser deposition technique.