U(1) Dirac quantum spin liquid candidate in triangular-lattice antiferromagnet CeMgAl${}_{11}$O${}_{19}$

Abstract

Quantum spin liquid represents an intriguing state where electron spins are highly entangled yet spin fluctuation persists even at 0 K. Recently, the hexaaluminates \textit{R}MgAl${}_{11}$O${}_{19}$ (\textit{R} = rare earth) have been proposed to be a platform for realizing the quantum spin liquid state with dominant Ising anisotropic correlations. Here, we report detailed low-temperature magnetic susceptibility, muon spin relaxation, and thermodynamic studies on the CeMgAl${}_{11}$O${}_{19}$ single crystal. Ising anisotropy is revealed by magnetic susceptibility measurements. Muon spin relaxation and ac susceptibility measurements rule out any long-range magnetic ordering or spin freezing down to 50 mK despite the onset of spin correlations below $\sim$0.8 K. Instead, the spins keep fluctuating at a rate of 1.0(2) MHz at 50 mK. Specific heat results indicate a gapless excitation with a power-law dependence on temperature, $C_m(T)\propto T^{\alpha }$. The quasi-quadratic temperature dependence with $\alpha$ = 2.28(4) in zero field and linear temperature dependence in 0.25 T support the possible realization of the U(1) Dirac quantum spin liquid state.

Accepted by Sci. China - Phys. Mech. Astron. 7 pages main text + 8 pages supplementary materials

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Cited by in corpus (5)

• Modified large-$N$ approach to gapless spin liquids, magnetic orders, and dynamics: Application to triangular lattice antiferromagnets
• Crystal-Field--Driven Magnetoelectricity in the Triangular Quantum Magnet CeMgAl${}_{11}$O${}_{19}$
• Crystal-Field--Driven Magnetoelectric Coupling in the Non-Kramers Hexaaluminate PrMgAl11O19
• Magnetic dilution in the triangular lattice antiferromagnet NaYb${}_{1-x}$Lu${}_x$O${}_2$
• Spin Excitation Continuum in the Exactly Solvable Triangular-Lattice Spin Liquid CeMgAl11O19