μSR study of the triangular Ising antiferromagnet ErMgGaO4

We present a detailed magnetic study of the triangular antiferromagnet ErMgGaO4. A point charge calculation under the single ion approximation reveals a crystal field ground state doublet with a strong Ising-like behavior of the Er3+ moment along the c axis. Magnetic susceptibility and specific heat measurements indicate no presence of magnetic transitions above 0.1 K and no evidence of residual entropy as the temperature approaches zero. Zero field (ZF) mu SR measurements shows no sign of static uniform or random field and longitudinal field (LF) mu SR measurements exhibit persistent spin fluctuations down to our lowest temperature of 25 mK. Our results provide evidence of a quantum spin liquid state in the triangular antiferromagnet ErMgGaO4.