arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.03157cond-mat.str-elcond-mat.mtrl-sci
收藏

蜂窝晶格Tb2Ir3Ga9中的倾斜反铁磁序和自旋动力学

Canted antiferromagnetic order and spin dynamics in the honeycomb-lattice Tb2Ir3Ga9

Feng Ye, Zachary Morgan, Wei Tian, Songxue Chi, Xiaoping Wang, Michael E. Manley, David Parker, Mojammel A. Khan, J. F. Mitchell, Randy Fishman

摘要:

单晶中子衍射,非弹性中子散射,体磁化测量,和第一性原理计算被用来调查蜂窝晶格$\rm Tb_2Ir_3Ga_9$的磁性。虽然$R\ln2$磁性对低温熵的贡献表明最低能量晶场二重态的$\rm J_{eff}=1/2$矩,但Tb $^{3+}$离子在12.5 K以下形成倾斜的反铁磁结构。由于Dzyalloshinskiii-Moriya相互作用,$ab$平面中的Tb矩通过$6^\circ$略微向$b$倾斜,每个分子式单元的倾斜矩为1.22 $μ_{\rm B} $。一个最小的$xxz$自旋哈密顿量被用来同时拟合沿高对称方向的自旋波频率和沿三个晶轴的磁化强度的场依赖性。需要考虑到所观察到的静态和动态特性的面内和面外耦合到第二近邻的长程磁相互作用。Tb矩间交换作用的$z$分量大于$x$和$y$分量。该化合物还表现出键依赖性交换,平行和垂直于4个$f$轨道的矩之间的最近交换耦合可忽略不计。尽管有$J_{\rm eff}=1/2$矩,自旋哈密顿量由大的面内各向异性$K_z \sim -1$ meV命名。DFT计算证实了反铁磁基态和大量的面间耦合在较大的Tb-Tb距离。

英文摘要:

Single crystal neutron diffraction, inelastic neutron scattering, bulk magnetization measurements, and first-principles calculations are used to investigate the magnetic properties of the honeycomb lattice $\rm Tb_2Ir_3Ga_9$. While the $R\ln2$ magnetic contribution to the low-temperature entropy indicates a $\rm J_{eff}=1/2$ moment for the lowest-energy crystal-field doublet, the Tb$^{3+}$ ions form a canted antiferromagnetic structure below 12.5 K. Due to the Dzyalloshinskii-Moriya interactions, the Tb moments in the $ab$ plane are slightly canted towards $b$ by $6^\circ$ with a canted moment of 1.22 $μ_{\rm B} $ per formula unit. A minimal $xxz$ spin Hamiltonian is used to simultaneously fit the spin-wave frequencies along the high symmetry directions and the field dependence of the magnetization along the three crystallographic axes. Long-range magnetic interactions for both in-plane and out-of-plane couplings up to the second nearest neighbors are needed to account for the observed static and dynamic properties. The $z$ component of the exchange interactions between Tb moments are larger than the $x$ and $y$ components. This compound also exhibits bond-dependent exchange with negligible nearest exchange coupling between moments parallel and perpendicular to the 4$f$ orbitals. Despite the $J_{\rm eff}=1/2$ moments, the spin Hamiltonian is denominated by a large in-plane anisotropy $K_z \sim -1$ meV. DFT calculations confirm the antiferromagnetic ground state and the substantial inter-plane coupling at larger Tb-Tb distances.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑