Interfacial control of domain structure and magnetic anisotropy in La0.67Sr0.33MnO3 manganite heterostructures

Structural domains in ferroic materials can be manipulated to achieve novel properties and functionalities of devices with multiple tunabilities. Herein, we report a study of tunable domain structures in ferroelastic ${\mathrm{La}}_0.67{\mathrm{Sr}}_0.33{\mathrm{MnO}}₃$ (LSMO) films via interfacial engineering. Distinct domain structures are formed in rhombohedral LSMO films depending on the crystallographic orientations of the orthorhombic ${\mathrm{NdGaO}}₃$ (NGO) substrates. A unidirectional lattice modulation is observed in LSMO films grown on $\mathrm{NGO}{(110)}_{\mathrm{Or}}$ substrates, whereas a unidirectional twinned-domain structure is generated by $\mathrm{NGO}{(001)}_{\mathrm{Or}}$ substrates (where Or in the subscript denotes orthorhombic notation). The orientation-dependent domain structures in LSMO films are controlled by anisotropic strain as well as interfacial oxygen octahedral coupling at the heterointerface between LSMO and NGO. The orbital occupancy and in-plane magnetic anisotropy are markedly affected by strain relief induced by the unidirectional structural domains in LSMO films. In addition, the structural results observed in LSMO/$\mathrm{NGO}{(001)}_{\mathrm{Or}}$ films further demonstrate that anisotropic strain is capable to disturb octahedral connectivity in epitaxial films. Our findings provide future directions to understand and control the domain structures in ferroelastic heterostructures of perovskite materials and open a pathway towards tailoring the desirable physical properties.