Atomically defined epitaxy and physical properties of strained La0.6Sr0.4MnO3 films

Abstract

La 0.6 Sr 0.4 MnO 3 thin films were fabricated on SrTiO3 (001) substrates using pulsed laser deposition with observing persistent intensity oscillation of reflection high-energy electron diffraction. By atomic force microscopy, the surface of resulting films was confirmed to be extremely flat, showing atomically smooth terraces and 0.4 nm high steps corresponding to a unit cell height of perovskite. The surface terminating atomic layer was unambiguously assigned to the MnO2 layer by coaxial impact collision ion scattering spectroscopy. Crystal symmetry of the films is distorted into a tetragonal one due to the strain to fulfill perfect in-plane matching with the substrate even for films as thick as 100 nm. Even for films as thin as 4 nm (10 unit cells), ferromagnetic transition takes place to induce a metallic state and large negative magnetoresistance is observed as well.

Band structure of strained Gd(0001) films

“…The extent of in-plane strain is clearly seen to affect magnetic properties of the manganese perovskites La 1Ϫx A x MnO 3 . [9][10][11][12][13][14][15][16][17] These are also local moment ferromagnetic systems. Unfortunately, the band structure must take into account a realistic model of the surface band structure and surface composition in such systems, which can be quite complex in alloys and perovskites, 64 -68 so that a comparison, similar to the one presented here, between the experimental band structures in the perovskite systems with theory presents a very significant challenge.…”

“…[3][4][5][6] Compression of gadolinium is seen to lead to a suppression of T c , 3,6 while expansion leads to an increase of T c . 7,8 Not only does strain affect the magnetic properties, as now detailed fairly extensively for the perovskites, [9][10][11][12][13][14][15][16][17] but it has long been established that the lattice constant has a profound influence on the electronic structure, 18 -20 even for the thinnest of thin films. [21][22][23][24][25][26] Gd͑0001͒ grown on Mo͑112͒ exhibits a substantial inplane expansive strain compared to a similar thickness of Gd͑0001͒ on W͑110͒.…”

The next 25 years of surface physics

“…magnetism. Furthermore, the influence of surfaces and interfaces on thin-film properties is of technological interest for the design of TMO devices [35].…”

The surface terminal layer and composition of the colossal magnetoresistance perovskite: La0.65Pb0.35MnO3

“…[13][14][15] The termination layer of La 1Ϫx A x MnO 3 , with xϭ0.35, has been consistently determined to be at least partly Mn-O. [8][9][10][11][12][13][14][15] Unfortunately, because the surface free energy is expected to be different with the bulk, surface segregation is expected and has been routinely observed in some manganese perovskite oxides. [8][9][10]16,17 This paper explores whether La 0.65 Pb 0.35 MnO 3 exhibits a similar surface composition to La 0.65 A 0.35 MnO 3 (AϭCa, Sr, Ba) thus has a similar surface free enthalpy.…”

“…The termination layer of the perovskite manganese oxides, La 1Ϫx A x MnO 3 (AϭCa, Sr, Ba;xϭ0.1,0.35) has been studied using angle resolved x-ray photoemission spectroscopy, [8][9][10] ion scattering spectroscopy, 11,12 and angleresolved photoemission. [13][14][15] The termination layer of La 1Ϫx A x MnO 3 , with xϭ0.35, has been consistently determined to be at least partly Mn-O.…”