Search

The advent of van der Waals (vdW) ferromagnetic (FM) and antiferromagnetic (AFM) materials offers unprecedented opportunities for spintronics and magneto‐optic devices. Combining magnetic Kerr microscopy and density functional theory calculations, the AFM‐FM transition is investigated and a surprising abnormal magneto‐optic anisotropy in vdW CrSBr associated with different magnetic phases (FM, AFM, or paramagnetic state) is discovered. This unique magneto‐optic property leads to different anisotropic optical reflectivity from different magnetic states, permitting direct imaging of the AFM Néel vector orientation and the dynamic process of the AFM‐FM transition within a magnetic field. Using Kerr microscopy, not only the domain nucleation and propagation process is imaged but also the intermediate spin‐flop state in the AFM‐FM transition is identified. The unique magneto‐optic property and clear identification of the dynamics process of the AFM‐FM phase transition in CrSBr demonstrate the promise of vdW magnetic materials for future spintronic technology. [ABSTRACT FROM AUTHOR]

Understanding the magnetotransport properties of SrRuO3 thin films and heterostructures is essential for both fundamental research and practical applications. While the anomalous Hall effect has been studied extensively, the longitudinal magnetotransport (i.e. magnetoresistance) is not well understood and requires further investigation. Herein, SrRuO3/SrTiO3(001) epitaxial film is used as a model system to systematically investigate the correlation between magnetoresistance and structure symmetry. As the thickness of the SrRuO3 film increases, a structural symmetry transition from tetragonal to orthorhombic occurs. At the same time, a clear sign reversal of magnetoresistance from negative to positive, accompanied by the appearance of strong anisotropy in magnetoresistance measured along the two perpendicular in‐plane axes, is observed. These findings further suggest that the correlation between structural symmetry and magnetoresistance is mediated by the modulations in magnetic anisotropy. These results clarified the relationships between structure symmetry, magnetoresistance, and magnetic anisotropy, which can pave a feasible way for harnessing the magnetotransport properties of SrRuO3 films and using this material in oxide‐based spintronic devices. [ABSTRACT FROM AUTHOR]

Effective control of magnetic anisotropy is important for developing spintronic devices. In this work, we performed a case study of stacking periods (N)-mediated reorientation of lateral magnetic anisotropy in ultrathin La0.67Ca0.33MnO3/SrRuO3 superlattices. As N increases from 1 to 15, the magnetic easy-axis switches from the orthorhombic [010] to [100]-axis. The maximum anisotropy constant of the superlattice (SL) (N = 15) reaches −1.83 × 105 erg/cm3. X-ray absorption spectroscopy and x-ray linear dichroism further suggest that the observed changes in lateral magnetic anisotropy are driven by in-plane orbital polarization. For SLs with small N, anisotropic strain-induced orbital polarization along the b-axis can result in the [010]-oriented magnetic easy axis. For SLs with large N, the dimension crossover from 2-dimension to 3-dimension could enhance the hybridization of Ru t2g and Mn d x 2 − y 2 orbitals, which can compete with the strain effect and switch the magnetic easy axis to [100]. Our results suggest a potential strategy for engineering magnetic anisotropy through the cooperation of strain engineering and interfacial orbital engineering. [ABSTRACT FROM AUTHOR]

Oxide heterostructures have great potential for spintronics applications due to their well‐defined heterointerfaces and vast functionalities. To integrate such compelling features into practical spintronics devices, effective control of the magnetic switching behavior is key. Here, continuous control of the magnetic coercive field in SrTiO3/SrRuO3 ultrathin heterostructures is achieved by oxygen vacancy (VO) engineering. Pulsed laser deposition of an oxygen‐deficient SrTiO3 capping layer can trigger VO migration into the SrRuO3 layer while avoiding the formation of Ru vacancies. Moreover, by varying the thickness and growth conditions of the SrTiO3 capping layer, the value of the coercive field (HC) in the ferromagnetic SrRuO3 layer can be continuously tuned. The maximum enhancement of HC at 5 K is 3.2 T. Such a wide‐range tunability of HC may originate from a VO‐induced enhancement of perpendicular magnetic anisotropy and domain wall pinning. This study offers effective approaches for controlling physical properties of oxide heterostructures via VO engineering, which may facilitate the development of oxide‐based functional devices. [ABSTRACT FROM AUTHOR]

Electron-electron (e-e) correlation and spin-orbit coupling (SOC) are two essential control parameters that determine the physical properties of transition-metal-oxide-based thin films and heterostructures. Here, by harnessing these two parameters, we report the systematic control of both ferromagnetism and in-plane magnetic anisotropy in La0.67Ca0.33MnO3/CaIr1-xRuxO3 (LCMO/CIRO) superlattices grown on NdGaO3 substrates. In these all-oxide epitaxial systems, we demonstrate that the e-e correlation and the SOC depend strongly on the chemical composition of CIRO layers. By simply increasing the Ru doping level x, we can significantly suppress the degradation of ferromagnetism in ultrathin LCMO layers and enhance the TC by ∼90 K. Moreover, we observe a clear reorientation of the magnetic easy axis from orthorhombic [010] to [100] as x decreased to 0, which may originate from the enhanced SOC. Our work provides an insight for utilizing the 4d/5d transition-metal-oxides to tune the functionality of magnetic heterostructures. [ABSTRACT FROM AUTHOR]