TY  - JOUR
AU  - Li, Yuesheng
AU  - Bachus, Sebastian
AU  - Deng, Hao
AU  - Schmidt, Wolfgang
AU  - Thoma, Henrik
AU  - Hutanu, Vladimir
AU  - Tokiwa, Yoshifumi
AU  - Tsirlin, Alexander A.
AU  - Gegenwart, Philipp
TI  - Partial Up-Up-Down Order with the Continuously Distributed Order Parameter in the Triangular Antiferromagnet TmMgGaO 4
JO  - Physical review / X
VL  - 10
IS  - 1
SN  - 2160-3308
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2020-00155
SP  - 011007
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000506597500001
DO  - DOI:10.1103/PhysRevX.10.011007
UR  - https://juser.fz-juelich.de/record/872664
ER  -