Thickness dependence of magnetoresistance in La–Ca–Mn–O epitaxial films

Abstract

Colossal magnetoresistance in excess of 106% has been obtained (at 110 K, H=6 T) in epitaxially grown La–Ca–Mn–O thin films. The as-deposited film exhibits a substantial magnetoresistance value of 39 000%, which is further improved by heat treatment. The magnetoresistance is found to be strongly dependent on film thickness, with the value reaching the maxima at ∼1000 Å thickness, and then reduced by orders of magnitude when the film is made thicker than ∼2000 Å. This behavior is interpreted in terms of lattice strain in the La–Ca–Mn–O films.

Mn55NMR and magnetization studies ofLa0.67Sr0.33Sidorenko1, Allodi2, Renzi3 et al. 2006Phys. Rev. B283191View full textAdd to dashboardCite

“…In the manganite films, the substrate-induced strain affects magnetoresistivity, 1,2,3 Curie temperature, 4 and magnetic microstructure 5,6 . In particular, the magnetic anisotropy energy in the thin manganite films strongly depends on strain and, therefore, on the substrate material, film thickness, and deposition parameters.…”

Influence of strain relaxation on magnetotransport properties of epitaxial La0.7Ca0.3MnO3films

“…In epitaxial films, biaxial strain has been reported to have very strong effect on the changes in T C and insulator-metal transition temperature (T IM ) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] . Several publications have reported that both T C and T IM can vary with film thickness [14][15][16][17][18][19][20][21][22][23] .…”

Spin-polarized quasiparticle transport in cuprate superconductors

“…However, further theoretical investigations revealed that the double exchange alone cannot quantitatively account for the observed CMR effect, and that the strong electron-phonon interaction arising from the Jahn-Teller splitting may be important [88,96]. The suggested relevance of the lattice effects on the conductivity and magnetism of these manganites is supported by increasing experimental evidence: a strong correlation between the thickness of epitaxial films and the corresponding magnetoresistance has been shown in La 0.7 Sr 0.3 MnO 3 [89,97], where the magnitude of negative magnetoresistance is substantially reduced for film thickness larger than a critical thickness within which the lattice distortion is relaxed; …”