Gap electroacoustic waves inPT-symmetric piezoelectric heterostructure near the exceptional point

The spectral properties of gap electroacoustic waves in aPT-symmetric structure of piezoelectrics of symmetry class 6 mm separated by a gap are theoretically investigated. The spectra were calculated for lead germanate (non-zero transverse piezoactivity) and barium titanate (symmetry class 4 mm-zero transverse piezoactivity). It has been established that at a certain level of losses and gain in piezoelectrics, the symmetric and antisymmetric modes intersect. The intersection point determines the singular point of thePT-symmetric structure. Beyond this point, there is a violation of the symmetric and antisymmetric distribution of electric fields in the gap of the slotted structure of two identical piezoelectrics, which is confirmed by the calculation of the electric field profiles. It is shown that the dependence of the amplitude on the frequency at an exceptional point has an extremely narrow resonance peak, which opens up the possibility of creating supersensitive sensors based onPT-symmetric physical structures.