Abstract
We present an experimental investigation of the magnetic structure in a tetramer system using neutron powder-diffraction and nuclear resonance techniques. We establish a commensurate antiferromagnetic ordering with a propagation vector . The order parameter follows a critical behavior near with a critical exponent in agreement with a three-dimensional universality class. Evidence is presented that a singlet state starts to form on tetramers at temperatures as high as 200 K, and its signature is preserved within the ordered state through a strong renormalization of the ordered magnetic moment on two nonequivalent copper sites and at 1.5 K.
- Received 11 January 2018
- Revised 26 June 2018
DOI:https://doi.org/10.1103/PhysRevB.98.054409
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