Spin excitations and quantum criticality in the quasi-one-dimensional Ising-like ferromagnet CoCl2·2D2O in a transverse field
Research output: Contribution to journal › Journal article › Research › peer-review
361 Downloads (Pure)
We present experimental evidence for a quantum phase transition in the easy-axis S = 3/2 anisotropic quasione-dimensional ferromagnet CoCl2 · 2D2O in a transverse field. Elastic neutron scattering shows that the magnetic order parameter vanishes at a transverse critical field μ0Hc = 16.05(4) T, while inelastic neutron scattering shows that the gap in the magnetic excitation spectrum vanishes at the same field value, and reopens for H>Hc. The field dependence of the order parameter and the gap are well described by critical exponents β = 0.45 ± 0.09 and zν close to 1/2, implying that the quantum phase transition in CoCl2 · 2D2O differs significantly from the textbook version of a S = 1/2 Ising chain in a transverse field. We attribute the difference to weak but finite three-dimensionality of the magnetic interactions.
Larsen, J., Schäffer, T. K., Hansen, U. B., Holm, S. L., Ahl, S. R., Toft-Petersen, R., Taylor, J., Ehlers, G., Jensen, J., Rønnow, H. M., Lefmann, K., & Christensen, N. B. (2017). Spin excitations and quantum criticality in the quasi-one-dimensional Ising-like ferromagnet CoCl2·2D2O in a transverse field. Physical Review B, 96(17), [174424 ]. https://doi.org/10.1103/PhysRevB.96.174424