@article{matsumoto_quantum_2024,

title = {A quantum critical Bose gas of magnons in the quasi-two-dimensional antiferromagnet YbCl_{3} under magnetic fields},

author = {Y. Matsumoto and S. Schnierer and J. A. N. Bruin and J. Nuss and P. Reiss and G. Jackeli and K. Kitagawa and H. Takagi},

url = {https://doi.org/10.1038/s41567-024-02498-w},

doi = {10.1038/s41567-024-02498-w},

year  = {2024},

date = {2024-05-09},

urldate = {2024-05-09},

journal = {Nat. Phys.},

volume = {20},

number = {7},

pages = {1131–1138},

abstract = {Bose–Einstein condensation (BEC) is a quantum phenomenon in which a macroscopic number of bosons occupy the lowest energy state and acquire coherence at low temperatures. In three-dimensional antiferromagnets, a magnetic-field-induced transition has been successfully described as a magnon BEC. For a strictly two-dimensional (2D) system, it is known that BEC cannot take place due to the presence of a finite density of states at zero energy. However, in a realistic quasi-2D magnet consisting of stacked magnetic layers, a small but finite interlayer coupling stabilizes marginal BEC but such that 2D physics is still expected to dominate. This 2D-limit BEC behaviour has been reported in a few materials but only at very high magnetic fields that are difficult to access. The honeycomb S = 1/2 Heisenberg antiferromagnet YbCl3 exhibits a transition to a fully polarized state at a relatively low in-plane magnetic field. Here, we demonstrate the formation of a quantum critical 2D Bose gas at the transition field, which, with lowering the field, experiences a BEC marginally stabilized by an extremely small interlayer coupling. Our observations establish YbCl3, previously a Kitaev quantum spin liquid material, as a realization of a quantum critical BEC in the 2D limit.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}