Signatures of quantum criticality in pure Cr at high pressure
The elemental antiferromagnet Cr at high pressure presents a new type of naked quantum critical point that is free of disorder and symmetry-breaking fields. Here we measure magnetotransport in fine detail around the critical pressure, P_c ~ 10 GPa, in a diamond anvil cell and reveal the role of quantum critical fluctuations at the phase transition. As the magnetism disappears and T → 0, the magntotransport scaling converges to a non-mean-field form that illustrates the reconstruction of the magnetic Fermi surface, and is distinct from the critical scaling measured in chemically disordered Cr:V under pressure. The breakdown of itinerant antiferromagnetism only comes clearly into view in the clean limit, establishing disorder as a relevant variable at a quantum phase transition.
Additional InformationCopyright © 2010 National Academy of Sciences. Edited by Laura H. Greene, University of Illinois at Urbana–Champaign, Urbana, IL, and approved June 28, 2010 (received for review April 13, 2010). Published ahead of print July 19, 2010. We acknowledge Arnab Banerjee and Peter Littlewood for enlightening discussions. The work at the University of Chicago was supported by National Science Foundation (NSF) Grant DMR-0907025. Author contributions: R.J., Y.F., and T.F.R. designed research; R.J., Y.F., and J.W. performed research; R.J. and T.F.R. analyzed data; and R.J., Y.F., J.W., and T.F.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.
Published - PNAS-2010-Jaramillo-13631-5.pdf