Two-dimensional pressure-induced electronic topological transition in Bi2Te3

A structural peculiarity of the electronic topological transition (ETT) occurring within the pressure stability range of the low-pressure rhombohedral phase I has been evidenced in Bi2Te3. On both sides of the ETT the structure remains unchanged. Nevertheless, precise investigation of x-ray diffraction patterns allows us to conclude that this ETT obeys the lamellar character of this compound but in a counterintuitive way. Indeed, the signature of this ETT can be detected only in the layers' plane in the pressure variation of the lattice parameter a with a 25% increase of the lattice modulus and a 68% decrease of its pressure derivative. On the contrary, no singularity occurs perpendicularly to the layers of the Bi2Te3 structure.