%0 Journal Article
%A Li, Yuesheng
%A Bachus, Sebastian
%A Deng, Hao
%A Schmidt, Wolfgang
%A Thoma, Henrik
%A Hutanu, Vladimir
%A Tokiwa, Yoshifumi
%A Tsirlin, Alexander A.
%A Gegenwart, Philipp
%T Partial Up-Up-Down Order with the Continuously Distributed Order Parameter in the Triangular Antiferromagnet TmMgGaO 4
%J Physical review / X
%V 10
%N 1
%@ 2160-3308
%C College Park, Md.
%I APS
%M FZJ-2020-00155
%P 011007
%D 2020
%X We show that frustrated quasidoublets without time-reversal symmetry can host highly unconventional magnetic structures with continuously distributed order parameters even in a single-phase crystal. Our study comprises a comprehensive thermodynamic and neutron diffraction investigation on the single crystal of TmMgGaO4, which entails non-Kramers Tm3+ ions arranged on a geometrically perfect triangular lattice. The crystal electric field randomness caused by the site-mixing disorder of the nonmagnetic Mg2+ and Ga3+ ions merges two lowest-lying crystal electric field singlets of Tm3+ into a ground-state quasidoublet. Well below Tc∼0.7  K, a small fraction of the antiferromagnetically coupled Tm3+ Ising quasidoublets with small inner gaps condense into two-dimensional up-up-down magnetic structures with continuously distributed order parameters, and give rise to the columnar magnetic neutron reflections below μ0Hc∼2.6  T, with highly anisotropic correlation lengths, ξab≥250a in the triangular plane and ξc<c/12 between the planes. The remaining fraction of the Tm3+ ions remain nonmagnetic at 0 T and become uniformly polarized by the applied longitudinal field at low temperatures. We argue that the similar model can be generally applied to other compounds of non-Kramers rare-earth ions with correlated ground-state quasidoublets.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000506597500001
%R 10.1103/PhysRevX.10.011007
%U https://juser.fz-juelich.de/record/872664