In-plane reversal of the magnetic anisotropy in (110)-oriented LaCoO3/La0.67Sr0.33MnO3 heterostructures

Abstract

The interface engineering of the complex oxides with strongly coupled degrees of freedom opens a wide space for the exploration of novel effects. La0.67Sr0.33MnO3 is one of the most typical complex oxides used for atomic level material engineering. Herein we reported an in-plane reversal of the magnetic anisotropy in (110)-oriented LaCoO3/La0.67Sr0.33MnO3 (LCO/LSMO) bilayers grown on (110)-oriented LaAlO3 substrates. Fixing the LSMO layer thickness to 8 nm and varying the LCO layer from 0 to 8 nm, totally six bilayers were fabricated. Without the LCO layer, the LSMO film exhibits an easy axis along the [1-10] direction. However, when the thickness of the LCO layer exceeds 1 nm, a signature of spin-reorientation appears; the easy axis turns from the [1-10] to the [001] direction below 225 K. This tendency is continuously enhanced by increasing the LCO. We reveal that lattice strains are different along these two directions. The magnetic anisotropy is not only controlled by lattice strain but also by structural distortion at interface. This work shows the great potential of the interface engineering with differently structured oxides for the exploration of novel functional materials.

Magnetic Anisotropy Induced by Orbital Occupation States in La0.67Sr0.33MnO3 Films

“…In this case, the eg electron of Mn 3+ preferentially occupies 3z 2 -r 2 orbital. According to Bruno model [24], this induces an easy magnetization axis along the [001] direction. Relatively, in BLF, ξ[001] < ξ[11̅ 0] leads to a compressed octahedral along the [001] direction , as shown in Fig.…”

“…La0.67Sr0.33MnO3 (LSMO), as a perovskite-type magnetic material, is a promising candidate for spintronics [21][22][23] material because of its room Curie temperature and 100% spin polarization [9]. For epitaxial thin films, different interfacial couplings cause different MA behaviors [1,[24][25][26]. MA in LSMO has been proved to be closely related to the occupation state of Mn 3d-orbital electrons [27].…”

“…The spin of 𝑒 g electron is coupled to the orbital by spin-orbital interaction, and the orbital is affected by the crystal symmetry. According to the Bruno model, [24] though the orbital magnetic moment is exceedingly small, its direction would affect the direction of the easy magnetization axis. The direction of orbital magnetic moment is determined by the occupation state of the 𝑒 g electron.…”