Strain effects and structural correlation in paraelectric tellurides*

PbTe and related tellurides have long been known for their outstanding thermoelectric properties, with a recent resurgence of interest in their complex local structure, quantum paraelectricity, and superconductivity. Despite its simple rocksalt structure, neutron and X-ray diffuse scattering data for PbTe indicate the existence of a Pb off-centering and the appearance of fluctuating local dipoles [1]. This surprising local reduction of symmetry is still not completely understood, and it opens the prospect of relating the peculiar local structure to complex functional properties. Furthermore, alloyed tellurides exhibit superconductivity at low charge-carrier densities. The soft polar modes and the low-density superconductivity are characteristics analogous to the quantum paraelectric SrTiO₃. In addition, the electronic subsystem in quantum paraelectrics is strongly affected by lattice strains; recent work indicates dramatic effects of plastic deformation in SrTiO₃, including evidence for significantly enhanced superconductivity and ferroelectricity [2]. Here, we combine diffuse X-ray scattering, charge transport, and NMR measurements to probe the effects of elastic/plastic strain on structural correlations, quantum paraelectricity, and superconductivity in tellurides.

[1] K.A. Holm et al., Phys. Rev. B, 102, 024112 (2020).

[2] S. Hameed, D. Pelc et al., Nat. Mat. 21, 54 (2022)