Ground state of a quantum critical system: neutron scattering on Ce(Ru1-xFex)2Ge2

Abstract

We present neutron scattering data on Ce(Ru1−xFex)2Ge2 that show that magnetic ordering in the vicinity of a quantum critical point is restricted to short length scales even though all moments that are present have lined up with their neighbors. We argue that order is not limited by crystallographic defects but rather that quantum fluctuations disorder the system and dilute the magnetic moments to such an extent that a percolation network forms. The latter naturally explains how E/T scaling is possible in a system whose apparent dimensionality is above the upper critical dimension. © 2007, American Physical Society