Epitaxial strain induced metal insulator transition in La0.9Sr0.1MnO3 and La0.88Sr0.1MnO3 thin films

Abstract

We are reporting an unexpected metal insulator transition at the ferromagnetic phase-transition temperature for thin films of La0.9Sr0.1MnO3 (<50 nm), grown on a (100) face of SrTiO3 substrate. For the thicker films (>50 nm), similar to the single crystal, no such transition is observed below TC. Additionally, we observe the suppression of the features associated with charge or orbital ordering in intentionally La-deficient thin films of La0.88Sr0.1MnO3 (<75 nm). In thin films, transmission electron microscopy reveals a compressive strain due to the epitaxial growth, that is, lattice parameters adopt those of the cubic lattice of SrTiO3. As the film thickness increases, coherent microtwinning is observed in the films and the films relax to a orthorhombic structure.

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

“…Compressive strain usually reduces the resistivity and shifts T C towards higher temperature. These effects have been confirmed in La 0.7 Ca 0.3 MnO 3 films 6,7 and La 0.7 Sr 0.3 MnO 3 films [8][9][10][11][12] grown on various substrates.…”

“…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] .…”

Structure, strain, and the ground state of the LaTiO3/LaAlO3superlattice

“…Importantly, the material property can be altered by the epitaxial strain through the strong couplings in TMO between the charge, spin, orbital, and lattice degrees of freedom [10,11]. For example, previous studies have shown that the superconducting [12,13], ferromagnetic (FM) [14], and metal-insulator transition temperature [15][16][17] can be controlled by the strain.…”

Substrate surface engineering for tailoring properties of functional ceramic thin films

“…Whereas the thick film (240 nm) shows the bulk-like behavior with a metalinsulator transition, T MI , at 220K followed by a transition to a charged ordered insulator at 170K, charge ordering is destroyed in the homogeneously strained thin films. Compressive epitaxial strain causes here the transition from a ferromagnetic insulator to a ferromagnetic metal [4]. Similarly, in thin films of the charge-ordered [CO] Pr 1/2 Ca 1/2 MnO 3 the robustness of the CO state depends strongly on the strains and thus on the film thickness as shown by Prellier et al [8] .…”