Magnetic field tuning of quantum spin excitations in a weakly coupled S=1/2 Heisenberg spin chain as seen from NMR
Magnetic field tuning of quantum spin excitations in a weakly coupled S=1/2 Heisenberg spin chain as seen from NMR
复制标题
从 NMR 观察到的弱耦合 S=1/2 海森堡自旋链中量子自旋激发的磁场调谐
DOI：
10.1103/physrevb.100.125126
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发表时间：
2019-09-12
影响因子：
3.7
通讯作者：
Pi, Li
中科院分区：
文献类型：
--
作者：
Ma, Long;Wang, Z.;Pi, Li
本文报道了准一维S = 1/2量子磁体CH_3 NH_3Cu（HCOO）（3）在Dzyaloshinskiii-Moriya（DM）相互作用下的自旋激发的NMR研究.在TN以上，自旋子激发在低温下从常数1/T-1观察到，这是由交错自旋磁化率贡献的。在温度低于T-N的低温下，1/T-1在弱磁场下开始变平。随着磁场强度的增加，1/T-1逐渐呈现幂律的温度依赖关系，指数从0增加到接近3，最后接近5，这分别是常规三维磁体中占主导地位的两磁振子拉曼过程和三磁振子散射对核弛豫贡献的典型特征.讨论了磁场调谐量子自旋激发的一种可能的物理机制，该机制与磁场作用下DM相互作用产生的增强的有效交错场有关。
We report our NMR study of the spin excitations in the quasi-one-dimensional S = 1/2 quantum magnet CH3NH3Cu(HCOO)(3) lying in the one-dimensional-three-dimensional crossover regime with DzyaloshinskiiMoriya (DM) interactions. Above TN, the spinon excitation is observed from the constant 1/T-1 at low temperatures contributed from the staggered spin susceptibility. At low temperatures well below T-N, the 1/T-1 begins to flatten out under weak magnetic fields. With the increasing field intensity, 1/T-1 tends to show a power-law temperature dependence gradually, with the index increasing from zero to similar to 3, and finally similar to 5, which are the respective typical characteristics for the dominating two-magnon Raman process and three-magnon scattering contributions to the nuclear relaxation in a conventional three-dimensional magnet. A possible physical mechanism for this magnetic field tuning of quantum spin excitations related with the enhanced effective staggered field created by the DM interactions under magnetic field is discussed.