Pressure-induced phase transition in the J1-J2 square lattice antiferromagnet RbMoOPO4Cl
Pressure-induced phase transition in the J1-J2 square lattice antiferromagnet RbMoOPO4Cl
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J1-J2 方晶格反铁磁体 RbMoOPO4Cl 中的压力诱导相变
DOI：
10.1103/physrevb.103.104406
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发表时间：
2021
影响因子：
3.7
通讯作者：
Hiroi Zenji
中科院分区：
文献类型：
--
作者：
Takeda Hikaru;Yamauchi Touru;Takigawa Masashi;Ishikawa Hajime;Hiroi Zenji
我们报道了在高达6.4GPa的高压下的磁化强度和核磁共振测量结果，这是一种具有竞争最近邻和次最近邻相互作用的受抑正方晶格反铁磁体。的NMR位移和转移的超精细耦合常数的压力依赖性的异常表明在2.6 GPa，这是可能打破镜像对称性，并触发交换相互作用的显着变化的结构相变。事实上，磁有序状态下的NMR谱揭示了从低于3.3 GPa的柱状反铁磁（CAF）顺序到高于3.9 GPa的Néel反铁磁（NAF）顺序的变化。自旋晶格弛豫率也表明了主磁涨落随压力从CAF型向NAF型的变化。虽然在3.3和3.9 GPa之间的中压区域的NMR谱显示CAF和NAF相共存，但某些组分显示具有持续自旋波动的顺磁行为，从而留下量子无序相的可能性。自旋涨落的易平面各向异性与不寻常的非单调的温度依赖性在环境压力下得到逆转的伊辛各向异性在高压下。自旋为1/2的系统的这种意外的各向异性行为可以归因于Mo电子的强自旋轨道耦合。
We report results of magnetization andNMR measurements under high pressure up to 6.4 GPa on, which is a frustrated square-lattice antiferromagnet with competing nearest-neighbor and next-nearest-neighbor interactions. Anomalies in the pressure dependencies of the NMR shift and the transferred hyperfine coupling constants indicate a structural phase transition at 2.6 GPa, which is likely to break mirror symmetry and triggers significant change of the exchange interactions. In fact, the NMR spectra in magnetically ordered states reveal a change from the columnar antiferromagnetic (CAF) order below 3.3 GPa to the Néel antiferromagnetic (NAF) order above 3.9 GPa. The spin lattice relaxation ratealso indicates a change of dominant magnetic fluctuations from CAF-type to NAF-type with pressure. Although the NMR spectra in the intermediate pressure region between 3.3 and 3.9 GPa show coexistence of the CAF and NAF phases, a certain component ofshows paramagnetic behavior with persistent spin fluctuations, leaving a possibility for a quantum disordered phase. The easy-plane anisotropy of spin fluctuations with unusual nonmonotonic temperature dependence at ambient pressure gets reversed to the Ising anisotropy at high pressures. This unexpected anisotropic behavior for a spin 1/2 system may be ascribed to the strong spin-orbit coupling of Mo-electrons.