Epitaxial strain and thickness dependent structural, electrical and magnetic properties of La_0.67Sr_0.33MnO₃ films

Abstract

The crystal structural quality and the strain induced by the substrate strictly impose the magnetic and transport properties of La 0.67 Sr 0.33 MnO 3 (LSMO) films. In particular, the magnetic anisotropy (MA) of epitaxial LSMO can be finely tuned by varying its thickness and by choosing single crystal substrates with suitable lattice mismatch with the film. Here, we have deposited LSMO films with thicknesses in the 12-50 nm range by pulsed laser deposition on different single crystal substrates inducing either compressive or tensile in-plane strain on the manganites. The epitaxial quality of films was quantified by ω-scans around (002) peak with full-width half-maximum (FWHM) values as low as 0.08° for films on the nearly matched NGO (110) substrate to 1.4° films on high mismatched MgO (001) substrate. As the epitaxial strain in thin-film increases, a significant reduction in metal-insulation transition (MIT) temperature (T p) was observed. The magnetic properties of the films probed by Kerr magnetometry show that the symmetry of the room temperature MA varies significantly as a function of both strain and thickness. Specifically, we observed pure uniaxial MA on NGO (110) and pure biaxial MA on STO buffered MgO (001), whereas a spin reorientation from uniaxial in-plane to out-of-plane on LSAT (001) and uniaxial to nearly isotropic in-plane on STO (001) substrate as the film thickness is increased. We provide an efficient tool to tune the MA according to the specific spintronic application targeted.

Tunable magnetic and magnetotransport properties in locally epitaxial La0.67Sr0.33MnO3 thin films on polycrystalline SrTiO3, by control of grain size

“…It is interesting to note, that outof-plane textured LSMO films [34] show TC values of about 340 K, only slightly higher than the single-crystal films [18]. It was shown that the TC of LSMO is strongly dependent with the different orientations (100), ( 110) or (111) orientation [39], and strain state of the film with a decrease of the Tc with compressive or tensile strain [29,40,41]. The mixed orientations of LSMO grains in CSE thin films, relaxe the strain at the grains boundries and explain the increase of TC in CSE compare to single-crystal films.…”

Influence of Thickness on the Magnetic and Magnetotransport Properties of Epitaxial La0.7Sr0.3MnO3 Films Deposited on STO (0 0 1)

“…Another study reported differences between T C values of La 0.67 Sr 0.33 MnO 3 films deposited by PLD on various substrates, such as GSO, STO, and NGO: 328, 334, and 338 K [50]. T P was found to increase with thickness, increase with compressive strain, and decrease with tensile strain [51]. When deposited on (Pb 0.97 La 0.02 ) (Zr 0.58 Sn 0.3025 Ti 0.1175 )O 3 (PLZST) ceramics, the La 0.7 Sr 0.3 MnO 3 films have T C values increasing with thickness reduction [52].…”

Strain Engineering: A Pathway for Tunable Functionalities of Perovskite Metal Oxide Films

“…Such epitaxial thin films have a ri ovskite metal oxides facilitated by the advances in thin-film growth te molecular beam epitaxy, pulse laser deposition, sputtering, metal-organ deposition, and chemical solution deposition. Biaxial strains in perov films can be used as a lever to tune physical properties such as electric p netoresistance and magnetic anisotropy, and stabilize metastable phas distort the perovskite structure by tilting, rotating, and elongating the o and therefore significantly affect the properties of given materials such a ture (TC) [10,[29][30][31], magnetic anisotropy [32][33][34][35][36][37], and magnetotransport (c + ) and the negative sign shows out-of-phase rotation (c − ), both about z-axis. Reprinted with permission from ref.…”

“…Biaxial strains in perovskite metal oxide films can be used as a lever to tune physical properties such as electric polarization, magnetoresistance and magnetic anisotropy, and stabilize metastable phases [9]. Strain can distort the perovskite structure by tilting, rotating, and elongating the oxygen octahedra, and therefore significantly affect the properties of given materials such as Curie temperature (T C ) [10,[29][30][31], magnetic anisotropy [32][33][34][35][36][37], and magnetotransport properties of ferromagnetic materials [38][39][40][41]. In ferroelectric perovskite oxides, for example, the epitaxial strain can enhance the T C for several hundreds of degrees [11,[42][43][44][45].…”