Pressure-dependent, low temperature inelastic light (Raman) scattering measurements of KCuF3 show that applied pressure above P∗∼ 7 kbar suppresses a previously observed structural phase transition temperature to zero temperature in KCuF3, resulting in the development of a ω∼ 0 fluctuational (quasielastic) response near T∼ 0 K. This pressure-induced fluctuational response --- which we associate with slow fluctuations of the CuF6 octahedral orientation --- is temperature independent and exhibits a characteristic fluctuation rate that is much larger than the temperature, consistent with quantum fluctuations of the CuF6 octahedra. A model of pseudospin-phonon coupling provides a qualitative description of both the temperature- and pressure-dependent evolution of the Raman spectra of KCuF3.
@article{arxiv.1107.1433,
title = {Inelastic light scattering measurements of a pressure-induced quantum liquid in KCuF$_3$},
author = {S. Yuan and M. Kim and J. Seeley and S. Lal and P. Abbamonte and S. L. Cooper},
journal= {arXiv preprint arXiv:1107.1433},
year = {2015}
}