Pressure-induced structural transition in copper pyrazine dinitrate and implications for quantum magnetism

K. R. O'Neal, The University of Tennessee, Knoxville
J. Zhou, Virginia Commonwealth University
J. G. Cherian, The University of Tennessee, Knoxville
M. M. Turnbull, Clark University
C. P. Landee, Clark University
P. Jena, Virginia Commonwealth University
Z. Liu, Carnegie Institution of Washington
J. L. Musfeldt, The University of Tennessee, Knoxville

Abstract

We combined synchrotron-based infrared and Raman spectroscopies, diamond anvil cell techniques, and first principles calculations to unveil pressure-induced distortions in quasi-one-dimensional Cu(pyz)(NO3)2. The crossover at 0.7 GPa is local in nature whereas the transition at 5 GPa lowers symmetry from Pmna to P2221 and is predicted to slightly increase magnetic dimensionality. Comparison with prior magnetoinfrared results reveals the striking role of out-of-plane bending of the pyrazine ligand, a finding that we discuss in terms of the possibility of using pressure to bias the magnetic quantum critical transition in this classic S=1/2 antiferromagnet.