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By using theoretical predictions based on first-principle calculations, we explore an interface engineering approach to stabilize polarization states in ferroelectric heterostructures with a thickness of just several nanometers.

We report appearance of the net magnetization in Mn-based antiperovskite compounds as a result of the external strain gradient (flexomagnetic effect). In particular, we describe the mechanism of the magnetization induction in the Mn3GaN at the atomic level in terms of the behavior of the local magnetic moments (LMM) of the Mn atoms. We show that the flexomagnetic effect is linear and results from the non-uniformity of the strain, i.e. it is absent not only in the ground state but also when the applied external strain is uniform. We estimate the flexomagnetic coefficient to be 1.95 µB Å . We show that at the moderate values of the strain gradient (∼ 0.1%) the flexomagnetic contribution is the only non-vanishing input to the induced magnetization.

Zhang, Jia; Lukashev, Pavel V.; Jaswal, Sitaram; and Tsymbal, Evgeny Y., "Model of orbital populations for voltage-controlled magnetic anisotropy in transition-metal thin films" (2017 Voltage-controlled magnetic anisotropy (VCMA) is an efficient way to manipulate the magnetization states in nanomagnets and is promising for low-power spintronic applications. The underlying physical mechanism for VCMA is known to involve a change in the d orbital occupation on the transition-metal interface atoms with an applied electric field. However, a simple qualitative picture of how this occupation controls the magnetocrystalline anisotropy (MCA) and even why in certain cases the MCA has the opposite sign remains elusive. In this paper, we exploit a simple model of orbital populations to elucidate a number of features typical for the interface MCA, and the effect of the electric field on it, for 3d transition-metal thin films used in magnetic tunnel junctions. We find that in all considered cases, including the Fe(001) surface, clean Fe 1−x Co x (001)/MgO interface, and oxidized Fe(001)/MgO interface, the effects of alloying and the electric field enhance the MCA energy with electron depletion, which is largely explained by the occupancy of the minority-spin d xz,yz orbitals. However, the hole-doped Fe(001) exhibits an inverse VCMA in which the MCA enhancement is achieved when electrons are accumulated at the Fe (001)/MgO interface with the applied electric field. In this regime, we predict a significantly enhanced VCMA that exceeds 1 pJ/Vm. Realizing this regime experimentally may be favorable for the practical purpose of voltage-driven magnetization reversal.

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