Ising-type quantum spin liquid state in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>PrMgAl</mml:mi> <mml:mn>11</mml:mn> </mml:msub> <mml:msub> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>19</mml:mn> </mml:msub> </mml:mrow> </mml:math>
N. Li, A. Rutherford, Yiyan Wang, Hui Liang, Q. J. Li, Zhanjun Zhang, Haozhe Wang, Weiwei Xie, Haidong Zhou, X. F. Sun
Abstract
We have grown single crystals of ${\mathrm{PrMgAl}}_{11}{\mathrm{O}}_{19}$, an ideal triangular-lattice antiferromagnet, and performed magnetic susceptibility, specific heat, and thermal conductivity measurements at low temperatures. The main results are as follows: (i) The temperature-dependent susceptibility shows a negligible in-plane response, and the isothermal magnetization curves confirm the easy axis along the $c$ axis. (ii) The specific heat measurements reveal the absence of long-range magnetic order down to 60 mK, and the power-law temperature dependence indicates the existence of the gapless magnetic excitations in the system. (iii) The ultralow-temperature thermal conductivity exhibits negligibly small residual term (${\ensuremath{\kappa}}_{0}/T$) and strong spin-phonon scattering effect, suggesting that the spin excitations are also involved. Our results further demonstrate that ${\mathrm{PrMgAl}}_{11}{\mathrm{O}}_{19}$ is a rare quantum spin liquid candidate with Ising-like anisotropy.