Detailed ${}^{31}$P nuclear magnetic resonance (NMR) measurements are presented on well-characterized single crystals of antiferromagnetic van der Waals Ni$_2$P$_2$S$_6$. An anomalous breakdown is observed in the proportionality of the NMR shift $K$ with the bulk susceptibility $χ$. This so-called $K$$-$$χ$ anomaly occurs in close proximity to the broad peak in $χ(T)$, thereby implying a connection to quasi-2D magnetic correlations known to be responsible for this maximum. Quantum chemistry calculations show that crystal field energy level depopulation effects cannot be responsible for the $K$$-$$χ$ anomaly. Appreciable in-plane transferred hyperfine coupling is observed, which is consistent with the proposed Ni$-$S$-$Ni super- and Ni$-$S$-$S$-$Ni super-super-exchange coupling mechanisms. Magnetization and spin$-$lattice relaxation rate ($T_1^{-1}$) measurements indicate little to no magnetic field dependence of the Néel temperature. Finally, $T_1^{-1}(T)$ evidences relaxation driven by three-magnon scattering in the antiferromagnetic state.
The ground state of $λ$-(BEDT-TTF)$_2$GaCl$_4$, which has the same structure as the organic superconductor $λ$-(BETS)$_2$GaCl$_4$, was investigated by magnetic susceptibility and $^{13}$C NMR measurements. The temperature dependence of the magnetic susceptibility revealed an antiferromagnetic (AF) correlation with $J/k_{\rm B} \simeq$ 98 K. NMR spectrum splitting and the divergence of $1/T_1$ were observed at approximately 13 K, which is associated with the AF transition. We found that the AF structure is commensurate according to discrete NMR peak splitting, suggesting that the ground state o…
Magnetic order and spin dynamics in La2O2Fe2OSe2 probed by 57Fe-Moessbauer, 139La-NMR, and muon spin relaxation spectroscopy
我们提出了一个详细的本地探针研究的磁顺序在氧硫属化物La 2 O2 Fe 2 OSe 2利用57 Fe穆斯堡尔谱，139 La NMR和μ子自旋弛豫谱。该系统可作为铁砷化物和硫属化物超导体的绝缘参考系。从本地探针技术的组合，我们确定了一个非共线的磁性结构类似于Sr 2F 2Fe 2 OS 2。磁序参量的分析产生的有序温度TN = 90.1 K和β = 0.133的临界指数，这是接近的二维伊辛普适类中报道的相关氧硫族化物家庭。
Magnetic properties of pure and Gd doped EuO probed by NMR
Eu NMR研究中的铁磁相的纯和Gd掺杂的EuO进行。一个完整的描述纯EuO的NMR线形允许掺杂EuO与Gd杂质的影响被突出。研究了Gd掺杂EuO的线形随温度的变化关系，证明了Gd掺杂EuO中存在随温度变化的静态磁不均匀性。结果表明，在0.6%Gd掺杂的EuO的不均匀性是与庞磁电阻。作为温度的函数的自旋-晶格弛豫时间的测量导致确定作为Gd掺杂的函数的交换积分J的值。结果发现，J是温度无关的和空间均匀的所有样品和它的值突然增加Gd掺杂。
9Be-NMR measurements were performed using single crystalline SmBe13 in order to investigate a magnetic structure of a low-temperature ordering state microscopically. We observed a spectral broadening in the ordered state, and the broadened spectral shape depends on the magnetic field directions. By comparing the experimentally obtained and simulated NMR spectra for magnetic fields along the cubic [001] and [011] directions, we argue a helical structure with a basal plane tilted from the (001) plane in low-field ordering region under the assumption of a helical with a propagation vector of (0, …
We present the synthesis and a detailed investigation of structural and magnetic properties of polycrystalline Ba(TiO)Cu$_{4}$(PO$_{4}$)$_{4}$ (BTCPO) via x-ray diffraction, magnetic susceptibility, heat capacity, and $^{31}$P Nuclear Magnetic Resonance (NMR) measurements. BTCPO has a 2D layered structure with interlinked Cu$_{4}$O$_{12}$ tetramer units. A broad maximum is observed around 16.5 K in our magnetization data accompanied by a sharp anomaly around $T$ = 9.5 K in the heat capacity. An anomaly at $T$ = 9.5 K is also found in the temperature dependence of the $^{31}$P NMR spin-lattice …
Phase Separation in A-site Ordered Perovskite Manganite LaBaMn$_2$O$_6$ Probed by $^{139}$La and $^{55}$Mn NMR
$^{139}$ La-和$^{55}$ Mn-NMR谱表明，A位有序钙钛矿锰氧化物LaBaMn $_2$ O $_6$的基态是铁磁（FM）和反铁磁（AFI（CE））区域的空间混合物，这分别被分配给金属和绝缘电荷有序状态。这种奇异的共存状态出现在200 K以下，通过一个一阶类似的形成的AFI（CE）状态内的FM之一。Mn自旋-自旋弛豫速率表明，$_2$中与AFI（CE）区共存的FM区与无序形式La $_{0.5}$ Ba $_{0.5}$ MnOPDMATHABMR的体FM相相同，尽管没有A位无序.这表明LaBaMn $_2$ O $_6$中FM区的介观性质而不是纳米性质。
Spin Susceptibility of Ga-Stabilized delta-Pu Probed by {69}^Ga NMR
Spin susceptibility of stabilized δphase in the Pu-Ga alloy is studied by measuring {69,71}^Ga NMR spectra and nuclear spin-lattice relaxation rate {69} T_{1} ^{-1} in the temperature range 5 - 350 K. The shift ({69}^K) of the {69,71}^Ga NMR line and {69}^ T_{1} ^{-1} are controlled correspondingly by the static and the fluctuating in time parts of local magnetic field arisen at nonmagnetic gallium due to transferred hyperfine coupling with the nearest f electron environment of the more magnetic Pu. The nonmonotonic with a maximum around 150 K behavior of {69}^K(T) χ_{s,5f}(T) is attributed to…
We report $^{75}$As nuclear magnetic resonance measurements on single crystals of RbFe$_{2}$As$_{2}$ and CsFe$_{2}$As$_{2}$. Taking previously reported results for KFe$_{2}$As$_{2}$ into account, we find that the anisotropic electronic correlations evolve towards a magnetic instability in the $A$Fe$_{2}$As$_{2}$ series (with $A$ = K, Rb, Cs). Upon isovalent substitution with larger alkali ions, a drastic enhancement of the anisotropic nuclear spin-lattice relaxation rate and decreasing Knight shift reveal the formation of pronounced spin fluctuations with stripe-type modulation. Furthermore, a…
Magnetic state dynamics in itinerant paramagnet UM3B2 (M= Co, Ir) probed by 11B NMR
我们对巡游顺磁体系U $M_{3}$ B $_{2}$（$M =$ Co，Ir）进行了$^{11}$ B NMR测量，研究了由于结构各向异性引起的$5f$ -电子的低维特性。最近的X射线分析表明，UIr $_3$ B $_2$具有与已知超晶格不同的调制结构。NMR谱在$ab$ -平面内的方位角变化表明，B原子占据单一位置，围绕B原子的配体排列通过绕c轴的三次或六次旋转而转向与另一配体相同的取向。这些结果与X射线的假设是一致的。为了评价一般磁化率（$χ_{q,ω}$）的温度（$T$）发展，进行了Knight位移和核自旋-晶格弛豫速率测量，并在UCo $_{3}$ B $_{2}$和UIr $_{3}$ B $_{2}$中鉴定出$χ_{q,ω}$的类似变化。在定义为$T^{*}\simeq50$ K的交叉点之上，$χ_{q,ω}$的演化在$q=0$处占主导地位，表明铁磁关联在高$T$区域发展;同时，在$T^{*}$之下，$χ_{q,ω}$中的$q=0$部分表现出饱和趋势，在有限$q$处突然出现不同类别的色散。这种特殊的磁关联被解释为反铁磁关联，并且在低$T$区域中磁态动力学的显著特征是反铁磁关联与铁磁分量同时出现。从U $M_{3}$ B $_{2}$晶格可能的低维性讨论了NMR实验中得到的独特的磁关联。
In frustrated spin-1/2 chains the competition between the nearest- and next-nearest-neighbor exchange interactions leads to a rich phase diagram that becomes even richer in the presence of perturbations in their material realizations. These effects are still largely unexplored, so that new insight into static and dynamic magnetism, in particular by sensitive local probes, is highly desired. Here we present a comprehensive $^{17}$O nuclear magnetic resonance study of $β$-TeVO$_4$, where the anisotropy of the main exchange interactions and additional weak interchain exchange interactions complem…
Doping dependence of Normal-state Property in the Iron-based Oxypnictide Superconductors LaFeAsO1-y probed by 57Fe-NMR and 75As-NMR/NQR
本文报道了贫氧铁基氧氮族化合物超导体LaFeAsO_{1-y} $. A microscopic phase separation between superconducting domains and magnetic domains is shown to take place in the underdoped sample, indicating a local inhomogeneity in association with the density distribution of oxygen deficiencies. As a result, 1/T_1T in the normal state of the superconducting domain decreases significantly upon cooling at both the Fe and As sites regardless of the electron-doping level in LaFeAsO_{1-y}. On the basis of this result, we claim that $ 1/T_1 T $ is not always enhanced by antiferromagnetic fluctuations close to an antiferromagn…
To investigate spin susceptibility in a superconducting (SC) state, we measured the $^{125}$Te-nuclear magnetic resonance (NMR) Knight shifts at magnetic fields ($H$) up to 6.5 T along the $b$ and $c$ axes of single-crystal UTe$_2$, a promising candidate for a spin-triplet superconductor. In the SC state, the Knight shifts along the $b$ and $c$ axes ($K_b$ and $K_c$, respectively) decreased slightly and the decrease in $K_b$ was almost constant up to 6.5 T. The reduction in $K_c$ decreased with increasing $H$, and $K_c$ was unchanged through the SC transition temperature at 5.5 T, excluding th…
We present a $^{125}$Te nuclear magnetic resonance (NMR) study in the three-dimensional spin web lattice Cu$_3$TeO$_6$, which harbors topological magnons. The $^{125}$Te NMR spectra and the Knight shift $\mathcal{K}$ as a function of temperature show a drastic change at $T_\text{S}\sim 40$ K much lower than the Néel ordering temperature $T_\text{N}\sim 61$ K, providing evidence for the first-order structural phase transition within the magnetically ordered state. Most remarkably, the temperature dependence of the spin-lattice relaxation rate $T_1^{-1}$ unravels spin-gap-like magnetic excitatio…
Site-Selective NMR in the Quasi-1D Conductor beta-Sr0.33V2O5
我们报告51 V NMR实验中的金属相的准一维（1D）导体β-Sr 0. 33V2O5。的奈特位移和四极分裂的所有六个钒网站被确定为一个功能的磁场的方向垂直于导电的b轴。三个一维结构单元的磁性是显着的异质性。特别地，V2梯单元在两个（V2a和V2b）位点之间显示出明显的电荷分离。在其中一个位置，Knight位移和1/（T1T）的绝对值随着温度的降低而急剧增加，表明铁磁相关的发展。
We report a $^{75}$As nuclear magnetic resonance study in LaFeAsO single crystals, which undergoes nematic and antiferromagnetic transitions at $T_\text{nem}\sim 156$ K and $T_N \sim 138$ K, respectively. Below $T_\text{nem}$, the $^{75}$As spectrum splits sharply into two for an external magnetic field parallel to the orthorhombic $a$ or $b$ axis in the FeAs planes. Our analysis of the data demonstrates that the NMR line splitting arises from an electronically driven rotational symmetry breaking. The $^{75}$As spin-lattice relaxation rate as a function of temperature shows that spin fluctuati…
The magnetic phase diagram of CuCrO2 was studied with a novel method of simultaneous Cu NMR and electric polarization techniques with the primary goal of demonstrating that regardless of cooling history of the sample the magnetic phase with specific helmet-shaped NMR spectra associated with interplanar disorder possesses electric polarization. Our result unequivocally confirms the assumption of Sakhratov et al. Phys. Rev. B \bf{94}, 094410 (2016) that the high-field low-temperature phase is in fact a 3D-polar phase characterised by a 3D magnetic order with tensor order parameter. In comparison…
We report the anomalous breakdown in the scaling of the microscopic magnetic susceptibility, as measured via the ${}^{31}$P nuclear magnetic resonance (NMR) shift $K$, with the bulk magnetic susceptibility $χ$ in the paramagnetic state of Mn$_2$P$_2$S$_6$. This anomaly occurs near $T_\mathrm{max} \sim 117$ K the maximum in $χ(T)$ and is therefore associated with the onset of quasi-two-dimensional (quasi-2D) magnetic correlations. The spin-lattice relaxation rate divided by temperature $(T_1T)^{-1}$ in Mn$_2$P$_2$S$_6$ exhibits broad peak-like behavior as a function of temperature, qualitativel…
Rb-NMR study has been performed on the quasi-one dimensional competing spin chain Rb2Cu2Mo3O12 with ferromagnetic and antiferromagnetic exchange interactions on nearest neighboring and next nearest neighboring spins, respectively. The system changes from a gapped ground state at zero field to the gapless state at H_C \simeq 2 T, where the existence of magnetic order below 1 K was demonstrated by a broadening of NMR spectrum, associated with a critical divergence of 1/T_1. In higher temperature region, 1/T_1 showed a power-law type temperature dependence, from which the field dependence of Lutt…
Metal-insulator transition was microscopically investigated by orbital-resolved nuclear magnetic resonance (OR-NMR) spectroscopy in a single crystal of vanadium dioxide VO$_2$. Observations of the anisotropic $^{51}$V Knight shift and the nuclear quadrupole frequency allow us to evaluate orbital-dependent spin susceptibility and $d$ orbital occupations. The result is consistent with the degenerated $t_{2g}$ orbitals in a correlated metallic phase and the $d$ orbital ordering in a nonmagnetic insulating phase. The predominant orbital pointing along the chain facilitates a spin-singlet formation…
