Possible Fermi Liquid in the Lightly Doped Kitaev Spin Liquid

We study the lightly doped Kitaev spin liquid (LDKSL) and find it to be the Fermi liquid. The LDKSL satisfies the two key properties of the standard Landau Fermi liquid: the low-energy quasiparticles are well defined and the Fermi sea has the quantized volume determined by Luttinger’s theorem. These features can be observed in angle-resolved photoemission spectroscopy measurements. Meanwhile, the LDKSL has the topological Kitaev spin liquid surrounding the Fermi sea. So the LDKSL violates the Wiedemann-Franz law and has a large Wilson ratio. These results have the potential experimental verifiability in iridates upon doping.

Figure 1

(a) A honeycomb lattice and (b) the $x$, $y$, and $z$ links joining $A$ and $B$ sublattices. ${\mathbf{l}}_1=(\sqrt{3}/2){\widehat{\mathbf{e}}}_1+\frac{1}{2}{\widehat{\mathbf{e}}}_2$ and ${\mathbf{l}}_2={\widehat{\mathbf{e}}}_2$ are the primitive vectors.

Figure 2

(a) The ARPES intensity $I(\mathbf{k},0)$ near the Fermi energy for the LDKSL at $x=0.1$. (b) The dispersions in ARPES measurements.

Figure 3

The estimation of the temperature-dependent Lorentz number for the LDKSL at $x=0.1$.