Anomalous magnetism in strained La1-xSrxCoO3 epitaxial films (0 ≤ x ≤ 0.5)

Abstract

Spin state controlling has always been a focus of intensive studies due to its importance for novel effect exploration and information technology. Complex oxides with competitive mechanisms are suitable objects of study for this purpose due to their susceptibility to external stimuli. Perovskite cobaltate La1-xSrxCoO3 is one of such oxides. Combined effects of lattice strains and hole-doping have been studied for the LSCO films with 0 ≤ x ≤ 0.5. It is found that the lattice strain, either tensile or compressive, destabilizes the ferromagnetic (FM) state of the epitaxial films, leading to a nonmagnetic state that extensively exists in a doping window embedding deep into the range of the FM phase in bulk counterparts. Density functional theory calculations reveal a distinct spin state transition due to the combined effects of lattice distortion and hole-doping, explaining the unique magnetic behaviors of LSCO.

Strain-induced structure and oxygen transport interactions in epitaxial La0.6Sr0.4CoO3−δ thin films

“…The temperature range 680-780°C was investigated, and isotope exchange experiments with samples of both LSCO strains were always performed simultaneously. Using time-of-flightsecondary ion mass spectrometry (ToF-SIMS), the threedimensional (3D) distribution of 18 O and 16 O was measured. Conversion of the 3D information to one-dimensional (1D) diffusion profiles was performed as depicted in Fig.…”

“…In the recorded data, the LSCO layer was easily identifiable by monitoring the secondary ion signals of either Co − , CoO − , or CoO 2 − . The Poisson corrected oxygen isotope secondary ion counts of 16 O − and 18 O − of the LSCO layer were measured and analyzed.…”

“…High enough concentration of the oxygen vacancies in perovskites might result in the doubling of the unit cell to form so-called Brownmillerite phase 12 . Such superstructure results in periodic bright and dark stripes on the high resolution scanning transmission electron microscopy (STEM) images [13][14][15] and typically it is not observed in Sr-doped LSCO at Sr substitution below 50% [16][17][18][19][20] . Recent computational studies on related LaCoO 3 21 also revealed that changes of the lattice strain can strongly influence the mobility of oxygen in certain directions.…”

Tuning the magnetic properties ofLa0.67Sr0.33CoO3−Liu1, Wang2, Liu3 et al. 2016Phys. Rev. B101100View full textAdd to dashboardCite

“…For example, the magnetic properties are very different when the LaCoO 3 films suffer from tensile or compressive strains [7][8][9][10], and the magnetization increases significantly with increasing tensile strain that favors high-spin-state Co 3+ ions [11,12]. An unexpected dependence of the magnetization on Sr content was also observed in La 1−x Sr x CoO 3 films [13]. The magnetization is weakened by introducing Sr ions into tensile La 1−x Sr x CoO 3 film (0.05 < x < 0.2), rather than enhanced as it is for its bulk counterpart.…”

Interface energetics and atomic structure of epitaxial La1−xSrxCoO3 on Nb:SrTiO3

“…[7][8][9] Electrical control of ferromagnetic behavior at submicron dimensions has recently been demonstrated in a LaCoO 3 (LCO)/SrTiO 3 (STO) field effect transistor device geometry. 8 The strain-dependent ferromagnetic properties of LaCoO 3 are thought to be associated with ordering of spin states in a stoichiometric lattice, or charge and orbital ordering caused by oxygen-vacancy superstructures.…”