论文标题
在Spin-3/2三角形抗fiferromagnet中具有无间隙的Dirac自旋基态的证据
Evidence for a gapless Dirac spin-liquid ground state in a spin-3/2 triangular-lattice antiferromagnet
论文作者
论文摘要
我们报告了对$ s $ = 3/2三角形抗fiferromagnet的磁性的全面研究，$α$ -CROOH（D）（Delafossites绿 - 灰色粉末）。几乎是海森伯格的反铁磁汉密尔顿（$ j_1 $ $ \ sim $ 23.5 k），具有弱的单离子各向异性为$ | d | $/$ j_1 $ $ \ sim $ 4.6％，是通过适合电子自旋（ESR RESONANCE（ESR）LINEWIDTH和高质量测量的Electron Spinance（ESR Resonance（ESR）和高音仪式测量的量子）。弱的单离子各向异性相互作用可能与其他扰动一起，例如下一个最新的 - 邻居相互作用，抑制远距离磁顺序并使系统混乱，这是由中子衍射中没有任何清晰的磁反射以及主要的磁性磁管ESR信号的存在所证明的，降低到2 K（$ \ sim $ 0.04 $ j_1 $ j_1 $ s^2 $），几乎是磁性磁带的位置。 The power-law behavior of specific heat ($C_m$ $\sim$ $T^{2.2}$) observed below the freezing temperature of $T_f$ = 25 K in $α$-CrOOH or below $T_f$ = 22 K in $α$-CrOOD is insensitive to the external magnetic field, and thus is consistent with the theoretical prediction of a gapless U(1) Dirac quantum spin liquid (QSL) ground state.在低温下，低能连续旋转激发的光谱重量在布里渊区的K点积聚，例如$ | \ mathbf {q} | $ = 4 $π$/（3 $ a $），并且明显可见推定的狄拉克锥。我们的工作是迈向理解此三角晶格磁铁中可能的狄拉克QSL基态状态的第一步，$ s $ = 3/2。
We report a comprehensive investigation of the magnetism of the $S$ = 3/2 triangular-lattice antiferromagnet, $α$-CrOOH(D) (delafossites green-grey powder). The nearly Heisenberg antiferromagnetic Hamiltonian ($J_1$ $\sim$ 23.5 K) with a weak single-ion anisotropy of $|D|$/$J_1$ $\sim$ 4.6% is quantitatively determined by fitting to the electron spin resonance (ESR) linewidth and susceptibility measured at high temperatures. The weak single-ion anisotropy interactions, possibly along with other perturbations, e.g. next-nearest-neighbor interactions, suppress the long-range magnetic order and render the system disordered, as evidenced by both the absence of any clear magnetic reflections in neutron diffraction and the presence of the dominant paramagnetic ESR signal down to 2 K ($\sim$ 0.04$J_1$$S^2$), where the magnetic entropy is almost zero. The power-law behavior of specific heat ($C_m$ $\sim$ $T^{2.2}$) observed below the freezing temperature of $T_f$ = 25 K in $α$-CrOOH or below $T_f$ = 22 K in $α$-CrOOD is insensitive to the external magnetic field, and thus is consistent with the theoretical prediction of a gapless U(1) Dirac quantum spin liquid (QSL) ground state. At low temperatures, the spectral weight of the low-energy continuous spin excitations accumulates at the K points of the Brillouin zone, e.g. $|\mathbf{Q}|$ = 4$π$/(3$a$), and the putative Dirac cones are clearly visible. Our work is a first step towards the understanding of the possible Dirac QSL ground state in this triangular-lattice magnet with $S$ = 3/2.
