We report $^{125}$Te and $^{63,65}$Cu nuclear magnetic resonance (NMR) studies on single crystals of staircase Kagomé antiferromagnet PbCu3TeO7 ($T_{N1}\approx$ 36 K). A Curie constant as large as $Θ$~140 K is obtained by a Curie-Weiss fitting of the high-temperature Knight shift. The frustration factor f (= $Θ/T_N $)$\approx$ 4 implies intermediate frustration in this system. From the high-temperature Knight shift data of $^{125}$Te, its hyperfine coupling constant is estimated to be $^{125}A_{hf}$ = -67 kOe/$μ_B$, which suggests a strong interlayer coupling bridging the neighboring Kagomé layers. At $T$= 2 K, we find two types of zero-field NMR signals. One has no dependence on the history of the field treatment, which is consistent with Cu NMR signals from inequivalent Cu sites with different internal hyperfine fields. The other one is only seen after a field-cycling process, which is consistent with domain wall contributions in this frustrated antiferromagnet.
The kagome staircase compounds Ni$_{3}$V$_{2}$O$_{8}$ and Co$_{3}$V$_{2}$O$_{8}$ studied with implanted muons
本文报道了可果美阶梯化合物Ni $_{3}$ V $_{2}$ O $_{8}$和Co $_{3}$ V $_{2}$ O $_{8}$的μ子自旋弛豫($μ^{+}$ SR)测量结果.这些材料的磁性行为可以用两个不等价的磁性离子位点来描述,称为脊柱位点和交叉结合位点。我们的$μ^{+}$ SR结果使我们能够单独探测这些位置中的每一个,揭示这些位置附近的局部磁场的分布。我们不仅能够确认的基础上提出的散装测量的各个阶段的磁结构,但也给在每个阶段的局部场分布的温度演变的洞察。
Low-temperature thermal conductivity and magnetic transitions of the kagomé-staircase compound Ni$_3$V$_2$O$_8$
Kagomé阶梯化合物Ni $_3$ V $_2$ O $_8$是一种具有丰富相图的多铁性材料。然而,磁性和磁转变仅在1.3K以上被研究。本文研究了Ni $_3$ V $_2$ O $_8$单晶在0.3 K低温和14 T磁场下的热导率($κ$)。在零磁场下,从低温无公度(LTI)相到公度相(C),再到第二公度相(C ')的磁跃迁分别在$T\rm_{LC}$ = 3.7 K和$T\rm_{CC'}$ = 2.0 K时产生$κ(T)$曲线的异常,表明临界自旋涨落对声子有明显的散射作用.当沿$a$轴施加磁场时,$κ$的场依赖性显示与不同的磁转变相关的四种异常,并揭示了在亚开尔文温度下未检测到的磁状态。此外,发现$κ(B)$曲线不仅与历史有关,而且与外加场的大小有关。当磁场沿$b$轴方向施加时,发现了位于LTI和高温无公度(HTI)相上方的高场相。
Magnetic Order and Fluctuations in the Presence of Quenched Disorder in the Kagome Staircase System (Co(1-x)Mg(x))3V2O8
Co 3V 2 O 8是一种正交晶系磁体,其中S=3/2磁矩位于两个晶体学上不等价的Co 2+位点上,其装饰了二维kagome晶格的堆叠的屈曲版本,堆叠的kagome楼梯。该结构中Co 2+磁矩之间的磁相互作用导致低温下的复杂磁相图,其中它在11 K以下表现出一系列的五个转变,最终在T~6.2 K以下达到简单铁磁基态。本文报道了(Co(1-x)Mg(x))_3V_2O_8单晶和多晶样品(x<0.23)的磁化强度测量结果,以及磁稀(Co(1-x)Mg(x))_3V_2O_8单晶(x=0.029和x=0.194)的弹性和非弹性中子散射测量结果。我们发现,2.9%的稀释导致铁磁转变温度的抑制约15%,而19.4%的稀释水平足以破坏该材料中的铁磁长程序,直到至少1.5 K的温度。磁激发谱的特征在于(Co(1-x)Mg(x))3V 2 O 8(x=0.029)的有序相中的两个自旋波分支,类似于纯x=0材料的自旋波分支,以及(Co(1-x)Mg(x))3V 2 O 8(x=0.194)在低于10 K的温度下的宽漫散射。这种强烈的依赖性的转变温度的长程序在淬火的非磁性杂质的存在下,与二维物理驱动的转变是一致的。我们进一步提供了一个简单的渗流模型,半定量地解释了这个系统无法建立远程磁秩序在不寻常的低稀释水平,我们在我们的实验中观察到。
Single-crystal growth, structural characterization, and physical properties of a decorated square-kagome antiferromagnet KCu$_7$TeO$_4$(SO$_4$)$_5$Cl
Chongqing University(重庆大学);Karlsruhe Institute of Technology(卡尔斯鲁厄理工学院);North China Electric Power University(华北电力大学);Renmin University of China(中国人民大学);Institute of Physics, Chinese Academy of Sciences(中国科学院物理研究所);Spallation Neutron Source Science Center(中国散裂中子源科学中心)
Collinear and noncollinear antiferromagnetic ordering in a highly frustrated decorated square kagomé lattice antiferromagnets of the nabokoite family
P.L. Kapitza Institute for Physical Problems, RAS(俄罗斯科学院P.L.卡皮察物理问题研究所);National Research University “HSE”(国立研究型大学高等经济大学);M.V. Lomonosov Moscow State University(莫斯科罗蒙诺索夫国立大学);National University of Science and Technology “MISiS”(国立科技大学米西斯大学)