Neutron scattering and muon spin relaxation measurements of the non-centrosymmetric antiferromagnet CeCoGe3
M. Smidman, D. T. Adroja, A. D. Hillier, L. C. Chapon, J. W. Taylor, V. K. Anand, R. P. Singh, M. R. Lees, E. A. Goremychkin, M. M. Koza, V. V. Krishnamurthy, D… 展开作者
M. Smidman, D. T. Adroja, A. D. Hillier, L. C. Chapon, J. W. Taylor, V. K. Anand, R. P. Singh, M. R. Lees, E. A. Goremychkin, M. M. Koza, V. V. Krishnamurthy, D. M. Paul, G. Balakrishnan
The magnetic states of the non-centrosymmetric, pressure induced superconductor CeCoGe3 have been studied with magnetic susceptibility, muon spin relaxation(muSR), single crystal neutron diffraction and inelastic neutron scattering (INS). CeCoGe3 exhibits three magnetic phase transitions at T_N1 = 21 K, T_N2 = 12 K and T_N3 = 8 K. The presence of long range magnetic order below T_N1 is revealed by the observation of oscillations of the asymmetry in the muSR spectra between 13 K and 20 K and a sharp increase in the muon depolarization rate. Single crystal neutron diffraction measurements reveal magnetic Bragg peaks consistent with propagation vectors of k = 2/3 between T_N1 and T_N2, k = 5/8between T_N2 and T_N3 and k = 1/2 below T_N3. An increase in intensity of the (1 1 0) reflection between T_N1 and T_N3 also indicates a ferromagnetic component in these phases. These measurements are consistent with an equal moment, two-up, two-down magnetic structure below T_N3, with a magnetic moment of 0.405(5) mu_B/Ce. Above T_N2, the results are consistent with an equal moment, two-up, one-down structure with a moment of 0.360(6) mu_B/Ce. INS studies reveal two crystal-field (CEF) excitations at 19 and 27 meV. From an analysis with a CEF model, the wave-functions of the J = 5/2 multiplet are evaluated along with a prediction for the magnitude and direction of the ground state magnetic moment. Our model correctly predicts that the moments order along the c axis but the observed magnetic moment of 0.405(5) mu_B is reduced compared to the predicted moment of 1.01 mu_B. This is ascribed to hybridization between the localized Ce^3+ f-electrons and the conduction band. This suggests that CeCoGe3 has a degree of hybridization between that of CeRhGe3 and the non-centrosymmetric superconductor CeRhSi3.
Comparative study of the centrosymmetric and non-centrosymmetric superconducting phases of Re3W using muon-spin spectroscopy and heat capacity measurements
Ni$_2$Mo$_3$O$_8$: zig-zag antiferromagnetic order an integer spin non-centrosymmetric honeycomb lattice
理论研究已经预测了锯齿形反铁磁有序蜂窝状化合物中拓扑磁振子的存在。在这里，我们报告的锯齿形AFM秩序的层状和非中心对称的蜂窝状镍酸盐Ni $_2$ Mo $_3$ O $_8$通过结合磁化强度，比热，X-射线和中子衍射和电子顺磁共振测量的发现。这是在整数自旋非中心对称结构（$P$ $_6$ 3 $mc$）中这种顺序的第一个例子。此外，二分蜂窝晶格的两个不同位点中的每一个具有独特的晶体场环境，分别为八面体和四面体Ni $^{2+}$，使得能够在每个子晶格上独立取代。Mg在八面体位置上取代Ni抑制了长程磁序，并导致弱铁磁状态。相反，Fe取代Ni提高了AFM有序化温度。因此，Ni $_2$ Mo $_3$ O $_8$提供了一个平台，在该平台上探索蜂窝上的$S = 1$的丰富物理学，其中存在与非中心对称的、形式上的压电极性晶体结构的竞争磁相互作用。
Nodeless time-reversal symmetry breaking in the centrosymmetric superconductor Sc$_5$Co$_4$Si$_{10}$ probed by muon-spin spectroscopy
本文采用低温电阻率、磁化强度、热容、μ子自旋旋转和弛豫（$μ$ SR）测量方法研究了Sc $_{5}$ Co $_{4}$ Si $_{10}$的超导性质。发现Sc $_{5}$ Co $_{4}$ Si $_{10}$ {具有Ⅱ型超导性，其超导转变温度为$T_\mathrm{C}= 3.5 (1)$，K.使用各向同性Bardeen-Cooper-Schrieffer型$s$ -波隙对称性与$2Δ/k_\mathrm{B}T_\mathrm{C} = 2.84(2)$，对从横向场$μ$ SR光谱获得的超流密度的温度依赖性进行了最佳建模。然而，零场μ子自旋弛豫不对称性揭示了$T_\mathrm{C}$以下的自发磁场的出现，表明时间反演对称性（TRS）在超导状态下被打破。虽然这种行为通常与非幺正或混合的单重态-三重态配对有关，但我们对金斯堡-朗道自由能的群论分析以及密度泛函理论计算表明，非常规机制是不太可能的。因此，我们假设TRS破缺可能通过传统的电子-声子过程发生。
Enhancement of Superconducting Transition Temperature due to the strong Antiferromagnetic Spin Fluctuations in Non-centrosymmetric Heavy-fermion Superconductor CeIrSi3 :A 29Si-NMR Study under Pressure
The magnetic ground state properties of non-centrosymmetric CePt$_3$B$_{1-x}$Si$_x$
本文用μ子自旋旋转和弛豫测量方法研究了非中心对称$f$ -电子金属间化合物CePt $_3$ B $_{1-x}$ Si $_x$的合金化系列。此外，我们包括化学计量的母体化合物CePt $_3$ B的高压磁化调查。从我们的数据中，我们建立的性质的磁基态性质的系列，推导出有序的磁矩作为化学计量的函数和洞察到有序的磁状态的对称性的演变与$x$。因此，我们可以验证的概念，样品系列的行为基本上可以理解的框架内的Doniach相图。此外，我们的研究结果提出了Dzyaloshinskiii-Moriya磁相互作用在相关电子材料中的作用及其对此类材料中磁波动的影响。
Effects of the three-dimensional interplanar coupling on the centrosymmetric skyrmion crystal formation in the frustrated stacked-triangular Heisenberg model
From magnetic order to quantum disorder: a $μ$SR study of the Zn-barlowite series of $S={\frac{1}{2}}$ kagomé antiferromagnets, Zn$_{x}$Cu$_{4-x}$(OH)$_{6}$FBr
Persistent dynamics in the S=1/2 quasi-one-dimensional chain compound Rb4Cu(MoO4)3 probed with muon-spin relaxation
本文报道了低维反铁磁体Rb_4Cu（MoO_4）_3的μ子自旋弛豫测量结果。在50 mK以下没有观察到长程磁序，这意味着T_N/J<0.005（其中J是沿自旋链的主要交换强度），链间交换与链内交换的有效比值为|J_perp/J| <2 x 10^-3，使该材料成为一维量子海森堡反铁磁体的一个极好的实现。我们探测了低温下的持续自旋激发，发现弹道自旋输运在0.3K以下的激发中占主导地位。
$μ$SR Insight into the Impurity Problem in Quantum Kagome Antiferromagnets
杂质，这是固有的存在于任何真实的材料，可能会发挥重要的作用，与自旋液体基态的阻挫自旋系统的磁性。我们通过μ子自旋谱研究ZnCu $_3$（OH）$_6$ SO $_4$（锌-金红石）来解决量子可果美反铁磁体中的杂质问题。我们表明，μ介子耦合到杂质磁性，源自铜锌intersite无序，和杂质是高度相关的kagome自旋，使我们能够通过近藤效应探测内在的kagome物理。局部磁化率的低温平台表明自旋液体基态是无带隙的。相应的自旋涨落表现出非常规的谱密度和有趣的场依赖性。
In-plane magnetic field induced double fan spin structure with $\textit{c}$-axis component in metallic kagome antiferromagnet YMn$_{6}$Sn$_{6}$
可果美晶格的几何阻挫性质使其成为平坦电子带、非平凡拓扑性质和新颖磁性的伟大宿主。当施加面内磁场时，金属可果美反铁磁体YMn $_{6}$ Sn $_{6}$表现出拓扑霍尔效应（THE）。THE通常与具有大Dzyaloshinskiii-Moriya相互作用的非中心对称磁体中skyrmion的纳米尺寸非共面自旋结构相关。在这里，我们使用单晶中子衍射，以确定磁场/温度依赖性的磁结构在YMn $_{6}$ Sn $_{6}$。我们发现，所观察到的THE不能产生的磁skyrmion晶格，而是从一个平面内场诱导的双扇自旋结构与$\textit{c}$轴组件（DFC）。我们的工作提供了实验基础，从微观理论可以建立理解所观察到的THE。
