%0 Journal Article
%A Li, Yuesheng
%A Bachus, Sebastian
%A Liu, Benqiong
%A Radelytskyi, Igor
%A Bertin, Alexandre
%A Schneidewind, Astrid
%A Tokiwa, Yoshifumi
%A Tsirlin, Alexander A.
%A Gegenwart, Philipp
%T Rearrangement of Uncorrelated Valence Bonds Evidenced by Low-Energy Spin Excitations in YbMgGaO 4
%J Physical review letters
%V 122
%N 13
%@ 1079-7114
%C College Park, Md.
%I APS
%M FZJ-2019-02804
%P 137201
%D 2019
%X dc-magnetization data measured down to 40 mK speak against conventional freezing and reinstateYbMgGaO4as a triangular spin-liquid candidate. Magnetic susceptibility measured parallel andperpendicular to thecaxis reaches constant values below 0.1 and 0.2 K, respectively, thus indicatingthe presence of gapless low-energy spin excitations. We elucidate their nature in the triple-axis inelasticneutron scattering experiment that pinpoints the low-energy (E≤J0∼0.2meV) part of the excitationcontinuum present at low temperatures (T<J0=kB), butcompletelydisappearing upon warming thesystem aboveT≫J0=kB. In contrast to the high-energy part atE>J0that is rooted in the breaking ofnearest-neighbor valence bonds and persists to temperatures well aboveJ0=kB, the low-energy oneoriginates from the rearrangement of the valence bonds and thus from the propagation of unpaired spins.We further extend this picture to herbertsmithite, the spin-liquid candidate on the kagome lattice, and arguethat such a hierarchy of magnetic excitations may be a universal feature of quantum spin liquids.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31012603
%U <Go to ISI:>//WOS:000463901800015
%R 10.1103/PhysRevLett.122.137201
%U https://juser.fz-juelich.de/record/862498