Fig. 3: Identification of long-range biaxial strain in MnO2/graphene superlattice via TEM.

a HAADF-STEM image (scale bar, 1 nm) recorded along the [002] direction with iFFT image (in the yellow square) showing the existence of CJTE in MnO2/graphene superlattice along with b its corresponding FFT pattern (scale bar, 5 nm−1). The calculated c εxx, d εyy, and e εxy strain components via GPA. f Distribution and g statistics analysis of ratios of orthometric strain εc versus εab.