1 research outputs found
Signatures of a gapless quantum spin liquid in the Kitaev material NaCoZnSbO
The honeycomb-lattice cobaltate NaCoSbO has recently been
proposed to be a proximate Kitaev quantum spin liquid~(QSL) candidate. However,
non-Kitaev terms in the Hamiltonian lead to a zigzag-type
antiferromagnetic~(AFM) order at low temperatures. Here, we partially
substitute magnetic Co with nonmagnetic Zn and investigate the
chemical doping effect in tuning the magnetic ground states of
NaCoZnSbO. X-ray diffraction characterizations reveal no
structural transition but quite tiny changes on the lattice parameters over our
substitution range . Magnetic susceptibility and specific heat
results both show that AFM transition temperature is continuously suppressed
with increasing Zn content and neither long-range magnetic order nor spin
freezing is observed when . More importantly, a linear term of the
specific heat representing fermionic excitations is captured below 5~K in the
magnetically disordered regime, as opposed to the
behavior expected for bosonic excitations in the AFM state. Based on the data
above, we establish a magnetic phase diagram of NaCoZnSbO.
Our results indicate the presence of gapless fractional excitations in the
samples with no magnetic order, evidencing a potential QSL state induced by
doping in a Kitaev system.Comment: 10 pages, 5 figure