Faure, QuentinTakayoshi, ShintaroSimonet, VirginieGrenier, BeatriceMansson, MartinWhite, Jonathan S.Tucker, Gregory S.Ruegg, ChristianLejay, PascalGiamarchi, ThierryPetit, Sylvain2019-07-262019-07-262019-07-262019-07-1010.1103/PhysRevLett.123.027204https://infoscience.epfl.ch/handle/20.500.14299/159391WOS:000474895000020Combining inelastic neutron scattering and numerical simulations, we study the quasi-one-dimensional Ising anisotropic quantum antiferromagnet BaCo2V2O8 in a longitudinal magnetic field. This material shows a quantum phase transition from a Neel ordered phase at zero field to a longitudinal incommensurate spin density wave at a critical magnetic field of 3.8 T. Concomitantly, the excitation gap almost closes and a fundamental reconfiguration of the spin dynamics occurs. These experimental results are well described by the universal Tomonaga-Luttinger liquid theory developed for interacting spinless fermions in one dimension. We especially observe the rise of mainly longitudinal excitations, a hallmark of the unconventional low-field regime in Ising-like quantum antiferromagnetic chains.Physics, MultidisciplinaryPhysicsbose-einstein condensationquantum phase-transitionlinear-chaintext::journal::journal article::research article