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

Abstract

Magnetic insulators with strong perpendicular magnetic anisotropy (PMA) play a key role in exploring pure spin current phenomena and developing ultralowdissipation spintronic devices, thereby it is highly desirable to develop new material platforms. Here we report epitaxial growth of La2/3Sr1/3MnO3 (LSMO)-SrIrO3 (SIO) composite oxide films (LSMIO) with different crystalline orientations fabricated by sequential two-target ablation process using pulsed laser deposition. The LSMIO films exhibit high crystalline quality with homogeneous mixture of LSMO and SIO at atomic level. Ferrimagnetic and insulating transport characteristics are observed, with the temperature-dependent electric resistivity well fitted by Mott variable-range-hopping model. Moreover, the LSMIO films show strong PMA. Through further constructing all perovskite oxide heterostructures of the ferrimagnetic insulator LSMIO and a strong spin-orbital coupled SIO layer, pronounced spin Hall magnetoresistance (SMR) and spin Hall-like anomalous Hall effect (SH-AHE) were observed. These results illustrate the potential application of the ferrimagnetic insulator LSMIO in developing all-oxide ultralow-dissipation spintronic devices.

Emergent quantum phenomena in atomically engineered iridate heterostructures

“…Given the strong SOC in the 5 d transition metal oxides, their interfaces with magnetic oxides provide vivid platforms to explore emergent magnetic phenomena and functionalities that could not be realized in the heterostructures comprised of either 3 d or 4 d complex oxides. Recent research endeavors have been mainly focused on two types of heterostructures, i.e., (ⅰ) the heterostructure of 5 d SrIrO 3 and 4 d SrRuO 3 [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] and (ⅱ) the heterostructure of 5 d SrIrO 3 and 3 d La 1-x Sr x MnO 3 [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] .…”

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

“…For instance, by altering the growth orientation, the MA of the SrRuO 3 and Ir-doped La 1−x Sr x MnO 3 films can be regulated. 14,35,36 Therefore, in oxide systems with strong MCA, it is possible to obtain sizable PMA via growing films along the MCA easy-axis. Furthermore, compared to bulk phases, the low-dimensional oxide films show unique orientation-dependent phenomena, such as symmetry breaking and spatial confinement, which can adjust the orbital polarization and occupied state, presenting additional opportunities to control the MA in TMOs.…”

“…Crystal orientation is a vital parameter governing the properties of materials and various anisotropy factors. , It directly determines the orientations of the structural symmetry axis and structural anisotropy, which greatly affect the MA. , Obviously, in the TMO films, MA is also dependent on the orientation. For instance, by altering the growth orientation, the MA of the SrRuO 3 and Ir-doped La 1– x Sr x MnO 3 films can be regulated. ,, Therefore, in oxide systems with strong MCA, it is possible to obtain sizable PMA via growing films along the MCA easy-axis. Furthermore, compared to bulk phases, the low-dimensional oxide films show unique orientation-dependent phenomena, such as symmetry breaking and spatial confinement, which can adjust the orbital polarization and occupied state, presenting additional opportunities to control the MA in TMOs. − Therefore, with the cooperation of interfacial engineering and crystal orientation, it is possible to realize outstanding PMA in TMO films.…”

“…In the field of modern spintronics, high-performance magnetic materials are essential for realizing multiple applications, such as in-memory computing, microwave communication, information perception, etc. , Transition-metal oxides (TMOs) are the potential candidates due to their abundant functionalities, including colossal magnetoresistance, low damping coefficient, high spin polarization, etc. − Additionally, they show great tunability in magnetic ordering structures among ferro-, ferri-, and antiferromagnetism coupled with metallicity or insulation. − These characteristics offer TMOs the advantage of developing diverse spintronics functionalities. On the other hand, magnets with strong perpendicular magnetic anisotropy (PMA), with typical anisotropy energy ( K U ) above 10 6 erg/cm 3 , have attracted perennial attention because of their advantages of reducing characteristic size while maintaining thermal stability in nanoscaled spintronic devices. − However, weak structural anisotropy and/or the spin–orbit coupling (SOC) effect limit the magnetic crystalline anisotropy (MCA) in most magnetic TMO films, resulting in in-plane magnetic anisotropy (MA) dominated by shape anisotropy. , This restricts the application of TMOs in PMA-based devices.…”

Escalated Phase Separation Driven Enhanced Magnetoresistance in Manganite/Iridate Epitaxial Heterostructures

“…[13][14][15][16][17][18][19] The 3d-5d TMO heterostructures have generated huge interest due to the possibility of achieving highly tuneable quantum phenomena and functionalities. [20][21][22][23] Magnetic and electronic studies of manganite/iridate heterostructures have been limited to manganite compositions exhibiting either ferromagnetic or antiferromagnetic [18,19,24,25] states, but heterostructures with phase competition are rare. When the manganite is in a critical composition regime (e.g., at the boundary between a ferromagnetic metal and an antiferromagnetic insulator), it can exhibit phase coexistence.…”