Lateral Modulation of Magnetic Anisotropy in Tricolor 3d–5d Oxide Superlattices

Abstract

Manipulating magnetic anisotropy (MA) purposefully in transition metal oxides (TMOs) enables the development of oxide-based spintronic devices with practical applications. Here, we report a pathway to reversibly switch the lateral magnetic easy-axis via interfacial oxygen octahedral coupling (OOC) effects in 3d–5d tricolor superlattices, i.e., [SrIrO3,mRTiO3,SrIrO3,2La0.67Sr0.33MnO3]10 (RTiO3: SrTiO3 and CaTiO3). In the heterostructures, the anisotropy energy (MAE) is enhanced over one magnitude to ∼106 erg/cm3 compared to La0.67Sr0.33MnO3 films. Moreover, the magnetic easy-axis is reversibly reoriented between (100) and (110) directions by changing the RTiO3. Using first-principles density functional theory calculations, we find that the SrIrO3 owns a large single-ion anisotropy due to its strong spin–orbit interaction. This anisotropy can be reversibly controlled by the OOC and then reorient the easy-axis of the superlattices. Additionally, it enlarges the MAE of the films via the cooperation with a robust orbital hybridization between the Ir and Mn atoms. Our results indicate that the tricolor superlattices consisting of 3d and 5d oxides provide a powerful platform to study the MA and develop oxide-based spintronic devices.

Emergence of Insulating Ferrimagnetism and Perpendicular Magnetic Anisotropy in 3d–5d Perovskite Oxide Composite Films for Insulator Spintronics

“…Therefore, it is feasible to obtain perovskite FMIs with strong PMA in LSMIO composite films. Considering the negligible compressive strain imposed by the SrTiO 3 substrates, the observed strong PMA is not due to magnetoelastic anisotropy, as observed previously in LSMO films or heterostructures when under large compressive strain. , The strong PMA is due to the magnetic crystalline anisotropy originating from strong spin-orbital coupling and Mn–O–Ir bonding. ,, …”

“…Considering the negligible compressive strain imposed by the SrTiO3 substrates, the observed strong PMA is not due to magneto-elastic anisotropy as been observed previously in LSMO films or heterostructures when under large compressive strain 24,25 . The strong PMA is due to the magnetic crystalline anisotropy originated from strong spin-orbital coupling and Mn-O-Ir bonding 21,22,29 To further understand the electrical properties of LSMIO composite films, we have performed the temperature-dependent electric resistivity measurements. As shown in Fig.…”

“…24,25 The strong PMA is due to the magnetic crystalline anisotropy originating from strong spin-orbital coupling and Mn−O−Ir bonding. 21,22,29 To further understand the electrical properties of LSMIO composite films, we have performed the temperature-depend-ent electric resistivity measurements. As shown in Figure 2e, the resistivity increases monotonically as the temperature decreases, indicating that all of the LSMIO composite films are insulators.…”

Orientation-Driven Strong Perpendicular Magnetic Anisotropy in La0.67Sr0.33MnO3–SrIrO3 Heterostructures

“…Figure S2 denotes that (110)-LSMO displays evident in-plane magnetic anisotropy (IMA) due to the large shape anisotropy, similar to that observed in (001)-LSMO. 28 In the case of LSMO−SIO heterosystems, as illustrated in Figure 3a, (001)-LS5 exhibits a spontaneous magnetization along the normal direction, consistent with (001)-LS2, which is not observed in (001)-LSMO. 28 This result can be attributed to the increased MCA caused by the large SOC of SIO, which partially drove the magnetic easy-axis away from the planar direction.…”

“…28 In the case of LSMO−SIO heterosystems, as illustrated in Figure 3a, (001)-LS5 exhibits a spontaneous magnetization along the normal direction, consistent with (001)-LS2, which is not observed in (001)-LSMO. 28 This result can be attributed to the increased MCA caused by the large SOC of SIO, which partially drove the magnetic easy-axis away from the planar direction. However, the easy-axis still tends to lie in-plane rather than out-of-plane, indicating an IMA property in the film due to the large shape anisotropy.…”