Transition metal oxides exhibit a plethora of electrical and magnetic properties described by their order parameters. In particular, ferroic orderings offer access to a rich spectrum of fundamental physics phenomena, in addition to a range of technological applications. The heterogeneous integration of ferroelectric and ferromagnetic materials is a fruitful way to design multiferroic oxides. The realization of freestanding heterogeneous membranes of multiferroic oxides is highly desirable. In this study, epitaxial BaTiO 3 /La 0.7 Sr 0.3 MnO 3 freestanding bilayer membranes are fabricated using pulsed laser epitaxy. The membrane displays ferroelectricity and ferromagnetism above room temperature accompanying the finite magnetoelectric coupling constant. This study reveals that a freestanding heterostructure can be used to manipulate the structural and emergent properties of the membrane. In the absence of the strain caused by the substrate, the change in orbital occupancy of the magnetic layer leads to the reorientation of the magnetic easy-axis, that is, perpendicular magnetic anisotropy. These results of designing multiferroic oxide membranes open new avenues to integrate such flexible membranes for electronic applications.

Li‐Ion Battery Cathodes In article 2212098, Jaekwang Lee, Sung‐Yoon Chung, and co‐workers demonstrate that a significant amount of oxygen loss can be induced exclusively by lattice strain even in pristine layered oxides, LiCoO2 and Li2MnO3, without any electrochemical Li extraction. Calculations based on density functional theory also clarify that shear strain, among many different modes of mechanical strain, provide a major contribution to the energetically favorable formation of oxygen vacancies, critically supporting the experimental observations.

Since the recognition of a significant oxygen-redox contribution to enhancing the capacity of Li transition-metal oxide cathodes, the oxygen release and subsequent structural variations together with capacity fading are critical issues to achieve better electrochemical performance. As most previous reports dealt with the structural degradation of cathodes after electrochemical cycling, it is fairly difficult to clarify how substantial the effect of lattice strain on the oxygen release will be while exclusively ruling out any electrochemical influences. By utilizing nanoindentation and mechanical surface polishing of single-crystal LiCoO 2 and Li 2 MnO 3 , the local variations of both the atomic structure and oxygen content are scrutinized. Atomic-column-resolved imaging reveals that local Li-M (M = Co and Mn) disordering and further amorphization are induced by mechanical strain. Moreover, substantial oxygen deficiency in the regions with these structural changes is directly identified by spectroscopic analyses. Ab initio density functional theory calculations also demonstrate energetically favorable formation of oxygen vacancies under shear strain. Providing direct evidence of oxygen release as a consequence of lattice strain, the findings in this work suggest that efficient strain relaxation will be of great significance for longevity of the anion framework in layered oxide cathodes.