Role of alkaline metal in the rare-earth triangular antiferromagnet KYbO2

Spin-liquid materials can be tailored by chemical substitutions. Here, the authors use thermodynamic measurements and electron spin resonance to show that replacing Na by K in triangular magnets of the $A$YbO${}₂$ family weakens the magnetic couplings and renders the Yb${}³⁺$ ion more isotropic. They map out the temperature-field phase diagram and demonstrate that the field-induced plateau phase corresponds to 1/2 of the saturated magnetization.