Abstract
We present experimental evidence for a quantum phase transition in the easy-axis anisotropic quasi-one-dimensional ferromagnet in a transverse field. Elastic neutron scattering shows that the magnetic order parameter vanishes at a transverse critical field (4) T, while inelastic neutron scattering shows that the gap in the magnetic excitation spectrum vanishes at the same field value, and reopens for . The field dependence of the order parameter and the gap are well described by critical exponents and close to , implying that the quantum phase transition in differs significantly from the textbook version of a Ising chain in a transverse field. We attribute the difference to weak but finite three-dimensionality of the magnetic interactions.
- Received 22 December 2016
- Revised 30 May 2017
DOI:https://doi.org/10.1103/PhysRevB.96.174424
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