ESR Study of Uniaxial Stress Effect on the Cubic K₂PbCu(NO₂)₆

Abstract

g-value of Cu²⁺ has been observed as a function of uniaxial stress parallel to the [001] axis. Its shift dg=(3.0±0.5)×10⁻⁵/Kg/cm² is proportional to the lattice compression and reflects a tetragonal order. The change in line width in each phase suggests the existence of a dynamical motion of Cu(NO₂)₆ coupled with Jahn Teller mode which averages an incommensurate tetragonal local order.