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

Interface engineering is an effective and feasible method to regulate the magnetic anisotropy of films by altering interfacial states between different films. Using the technique of pulsed laser deposition, we prepared La0.67Sr0.33MnO3 (LSMO) and La0.67Sr0.33MnO3/SrCoO2.5 (LSMO/SCO) films on the (110)-oriented La0.3Sr0.7Al0.65Ta0.35O3 substrates. By covering the SCO film above the LSMO film, we transformed the easy magnetization axis of LSMO from the [001] axis to the [1\(\stackrel{\text{-}}{\text{1}}\)0] axis in the film plane. Based on statistical analyses, we found that the corresponding Mn-Mn ionic distances are different in the two types of LSMO films, causing different distortions of Mn-O octahedron in the LSMO film. In addition, it also induces diverse electronic occupation states in Mn3+ ions. The eg electron of Mn3+ occupies 3z2-r2 and x2-y2 orbitals in the LSMO and LSMO/SCO, respectively. We conclude that the electronic spin reorientation leads to the transformation of the easy magnetization axis in the LSMO films.

Origin of Ising magnetism in Ca3Co2O6 unveiled by orbital imaging

The one-dimensional cobaltate Ca$${}_{3}$$3Co$${}_{2}$$2O$${}_{6}$$6 is an intriguing material having an unconventional magnetic structure, displaying quantum tunneling phenomena in its magnetization. Using a newly developed experimental method, $$s$$s-core-level non-resonant inelastic x-ray scattering ($$s$$s-NIXS), we were able to image the atomic Co $$3d$$3d orbital that is responsible for the Ising magnetism in this system. We can directly observe that corrections to the commonly accepted ideal prismatic trigonal crystal field scheme occur in Ca$${}_{3}$$3Co$${}_{2}$$2O$${}_{6}$$6, and it is the complex $${d}_{2}$$d2 orbital occupied by the sixth electron at the high-spin Co$${}_{\,\text{trig}\,}^{3+}$$trig3+ ($${d}^{6}$$d6) sites that generates the Ising-like behavior. The ability to directly relate the orbital occupation with the local crystal structure is essential to model the magnetic properties of this system.

Optimizing the orbital occupation in the multiple minima problem of magnetic materials from the metaheuristic firefly algorithm

We present the use and implementation of the firefly algorithm to scan the multiple metastable minima of orbital occupations in density functional theory plus Hubbard U and to identify the ground state occupations in strongly correlated materials.