Fig. 3: Polymorphic-change mechanism in the MnTe device.

a High-resolution transmission electron microscopy (HR-TEM) image in the \(\left[ {0\bar 10} \right]\) zone axis of the α-matrix from the area enclosed by the black line in the upper left inset. Scale bar: 5 nm. The upper left inset corresponds to the scanning transmission electron microscopy (STEM) image of Fig. 2b, where the TEM sample was additionally ion milled. Scale bar: 100 nm. b Inverse fast Fourier transform (IFFT) images of annular dark-field STEM (ADF-STEM) images of the α (upper)- and β′ (bottom)-phases from the areas enclosed by red (right side) and blue (left side) lines, respectively. Scale bar: 5 Å. c Projection of atoms in the β (left)- and β′ (right)-phases viewed from the [010] direction, solid atoms are in the \(\left( {\bar 120} \right)\) plane, and semi-transparent atoms in the neighboring plane. d Polymorphic-change mechanism between the α- and β′-phases through alternate atomic-plane shuffling. Upper images show a crystal structure of the α (left)- and β′ (right)-phases. Middle images show a projection of atoms in the α (left)- and β′ (right)-phases viewed from the [001] direction. Bottom images present a projection of atoms on the light-blue colored plane in the α (\(\left( {\bar 120} \right)\), left)- and β′ ((\(\left( {\bar 120} \right)\)), right)-phase structure. The dotted arrows indicate the shuffling direction of each atomic-plane for the polymorphic-change from the α- to β′-phase (left) and from the β′- to α-phase (right).