We performed inelastic neutron scattering experiment to study magnetic excitation of O$_2$ molecules adsorbed in microporous compound. The dispersionless excitation with characteristic intensity modulation is observed at $\hbar ω= 7.8$ meV at low temperature. The neutron cross section is explained by spin dimer model with intradimer distance of 3.1 Å. Anomalous behaviour in the temperature dependence is discussed in the context of enhanced magnetoelasticity in the soft framework of O$_2$ molecule.
Recent progress in the fabrication techniques of superlattices (SLs) has made it possible to sandwich several-layer-thick block layers (BLs) of heavy-fermion superconductor CeCoIn5 between conventional-metal YbCoIn5 BLs or spin-density-wave-metal CeRhIn5 BLs of a similar thickness. However, the magnetic state in each BL, particularly at the interface, is not yet understood, as experimental techniques applicable to the SL system are limited. Here, we report measurements of 59Co nuclear magnetic resonance, which is a microscopic probe of the magnetic properties inside the target BLs. In the CeCo…
Oxygen vacancies play a crucial role in the control of the electronic, magnetic, ionic, and transport properties of functional oxide perovskites. Rare earth nickelates (RENiO$_{3-x}$) have emerged over the years as a rich platform to study the interplay between the lattice, the electronic structure, and ordered magnetism. In this study, we investigate the evolution of the electronic and magnetic structure in thin films of RENiO$_{3-x}$, using a combination of X-ray absorption spectroscopy and imaging, resonant X-ray scattering, and extended multiplet ligand field theory modeling. We find that …
Enhancement of giant magnetoresistance effect in the Ruddlesden-Popper phase Sr3Fe2-xCoxO7-d: Predominant role of oxygen nonstoichiometry and magnetic phase separation
The relative significance of quantum conductivity correction and magnetic nature of electrons in understanding the intriguing low-temperature resistivity minimum and negative magnetoresistance of the two-dimensional electron gas at LaAlO3/SrTiO3 interfaces has been a long outstanding issue since its discovery. Here we report a comparative magnetotransport study on amorphous and oxygen-annealed crystalline LaAlO3/SrTiO3 heterostructures at a relatively high-temperature range, where the orbital scattering is largely suppressed by thermal fluctuations. Despite of a predominantly negative out-of-p…
Magnetic properties of bilayer Sr$_3$Ir$_2$O$_7$: role of epitaxial strain and oxygen vacancies
用{ \it ab initio}方法研究了SrIridates Ruddlesden-Popper系列SrPDMATHABMO Ir $_{m}$ O $_{3m+1}$，双层结构SrPDMATHABMR Ir $_2$ O $_7$的磁性随外延应变和氧空位的变化.与单层化合物Sr $_2$ IrO $_4$不同，其表现出稳健的面内磁序，Sr $_3$ Ir $_2$ O $_7$中的面内和面外磁序之间的能量差小得多，并且预计小的外部扰动可以诱导磁跃迁。我们的研究结果表明，外延应变产生的自旋翻转转变，这是由之间的交叉层$J_1$和层间$J_2$磁交换相互作用压缩应变。$J_1$对应变效应基本上不敏感，而$J_2$的强度在拉伸应变$\geq$ 3~ 1%时变化一个数量级。此外，我们的研究澄清了不寻常的平面内观察到的磁响应在Sr $_3$ Ir $_2$ O $_7$的应用程序时的外部磁场源于由于氧空位，倾斜的八面体网络的局部磁矩的倾斜-从而允许非共线的自旋配置。
Artificial perovskite-oxide nanostructures possess intriguing magnetic properties due to their tailorable electron-electron interactions, which are extremely sensitive to the oxygen coordination environment. To date, perovskite-oxide nanodots with sizes below 50 nm have rarely been reported. Furthermore, the oxygen octahedral distortion and its relation to magnetic properties in perovskite oxide nanodots remain unexplored yet. Here, we have studied the magnetic anisotropy in patterned SrRuO3 (SRO) nanodots as small as 30 nm while performing atomic-resolution electron microscopy and spectroscop…
Magnetic adatom chains on surfaces constitute fascinating quantum spin systems. Superconducting substrates suppress interactions with bulk electronic excitations but couple the adatom spins to a chain of subgap Yu-Shiba-Rusinov (YSR) quasiparticles. Using a scanning tunneling microscope, we investigate such correlated spin-fermion systems by constructing Fe chains adatom by adatom on superconducting NbSe$_2$. The adatoms couple entirely via the substrate, retaining their quantum spin nature. In dimers, we observe that the deepest YSR state undergoes a quantum phase transition due to Ruderman-K…
Effect of Oxygen Content on Magnetic Properties of Layered Cobaltites PrBaCo2O5+δ
研究了氧含量对层状钙钛矿磁性能的影响。采用溶胶-凝胶法制备了PrBaCo $_{2}$ O $_{5+δ}$（0.35 $\leq δ\leq$ 0.80）样品，并通过X射线衍射和直流磁化进行了表征。给出了PrBaCo $_{2}$ O $_{5+δ}$的详细磁相图。据发现，与较重的稀土的情况下，铁磁相互作用是存在于所有温度低于Tc，甚至在反铁磁有序相。此外，在具有较低氧含量的化合物中，短程铁磁相互作用甚至在Tc以上也存在。这些层状钙钛矿中的磁性对氧含量的依赖性与Co离子周围多面体的变化有关。
Vacancy defects and monopole dynamics in oxygen-deficient pyrochlores
自旋冰中的磁单极子的想法在中温下取得了很大的成功，但在低温下，仅仅用磁动力学的描述是不够的。最近，数值模拟被用来争论磁性杂质通过在系统中引入剩余电阻的磁性等效物来解释这种差异。在这里，我们提出，氧的缺乏是主要原因的磁性杂质在生长的样品，我们确定的缺陷结构和磁性的Y2 Ti 2 O（7-δ）的漫中子散射和磁化测量。这些缺陷通过氧退火消除。氧空位的引入导致Ti 4+转变为具有淬灭轨道磁性的磁性Ti 3+，但浓度非常低。在自旋冰材料Dy 2 Ti 2 O 7中，我们发现相同的氧空位缺陷抑制了相邻稀土站点上的时刻，并且这些磁扭曲在亚开尔文温度下显着减缓了长时间的磁动力学。
Role of oxygen-oxygen hopping in the three-band copper-oxide model: quasiparticle weight, metal insulator and magnetic phase boundaries, gap values and optical conductivity
Coulomb interaction in oxygen \textit{p}-shell in LDA+U method and its influence on calculated spectral and magnetic properties of transition metal oxides
We report the structural, magnetic, exchange bias and magnetotransport effect in Sr$_{4}$Fe$_{3}$CoO$_{11}$. The material crystallizes in the orthorhombic $\textit{Cmmm}$ space group. It shows antiferromagnetic (G-type) transition (T$_{N}$ = 255 K) along with interesting temperature induced magnetization reversal (T$_{Comp.}$= 47 K measured at 100 Oe). The magnetic reversal can be elucidated considering the increased magnetocrystalline anisotropy with Co substitution. Magnetoresistance measurements shows an interesting crossover from negative to positive side at $\sim$ 100 K. The negative magn…
Two dimensional multiferroics inherit prominent physical properties from both low dimensional materials and magnetoelectric materials, and can go beyond their three dimensional counterparts for their unique structures. Here, based on density functional theory calculations, a MXene derivative, i.e., i-MXene (Ta$_{2/3}$Fe$_{1/3}$)$_2$CO$_2$, is predicted to be a type-I multiferroic material. Originated from the reliable $5d^0$ rule, its ferroelectricity is robust, with a moderate polarization up to $\sim12.33$ $μ$C/cm$^2$ along the a-axis, which can be easily switched and may persist above room …
Exploring d-Wave Magnetism in Cuprates from Oxygen Moments
Technical University of Munich（慕尼黑工业大学）；Xi’an Jiaotong University（西安交通大学）；University of Warsaw（华沙大学）；Goethe-Universität Frankfurt（法兰克福歌德大学）；Imperial College London（伦敦帝国理工学院）
Effect of oxygen isotope substitution and crystal micro-structure on magnetic ordering and phase separation in {$\rm (La_{1-y}Pr_{y})_{0.7}Ca_{0.3}MnO_3$}
In our previously published work, we have reported colossal magnetoresistance, Andreev oscillations, ferromagnetism, and granular superconductivity in oxygen-implanted carbon fibers, graphite foils, and highly oriented pyrolytic graphite. In this follow-up research, more results on these oxygen-implanted graphite samples are presented. We show results from transport measurements on oxygen-implanted diamond-like carbon thin coatings, amorphous carbon films, and highly oriented pyrolytic graphite. Significantly, a three-order magnitude drop in the electrical resistance of the oxygen-implanted di…
Critical-doping universality for cuprate superconductors: Oxygen nuclear-magnetic-resonance investigation of Ca(x)La(1-x)Ba(1.75-x)La(0.25+x)Cu(3)O(y)
在铜酸盐中，基态会改变其性质（从反铁磁体到自旋玻璃，再到超导体，再到金属）的临界掺杂水平并不普遍。我们调查的起源，这些关键的掺杂变化，通过测量的面内的氧$p_σ$空穴密度的CuO $_{2}$层中的氧密度$y$的函数（Ca $_{x}$ La $_{1-x}$）（Ba $_{1.75-x}$ La $_{0.25+x}$）铜$_{3}$ O $_{y}$。这是使用氧17核四极共振参数$ν_{Q}$完成的。我们比较化合物与$x=0.1$和0.4有显着的关键$y$的变化，并发现这些变化可以解释的空穴注入到$p_σ$轨道的效率的变化。这使我们能够在整个掺杂范围内为CLBLCO系统生成统一的相图，而无需可调参数。
Magneto-elastic coupling between copper spin configurations and oxygen octahedra in La(2-x)Sr(x)CuO(4). Untwinning, Raman (phonon) spectrum, and neutron response
Room temperature ferromagnetism was characterized for thin films of SrTi$_{0.6}$Fe$_{0.4}$O$_{3-δ}$ grown by pulsed laser deposition on SrTiO$_{3}$ and Si substrates under different oxygen pressures and after annealing under oxygen and vacuum conditions. X-ray magnetic circular dichroism demonstrated that the magnetization originated from Fe$^{2+}$ cations, whereas Fe$^{3+}$ and Ti$^{4+}$ did not contribute. Films with the highest magnetic moment (0.8 μB per Fe) had the highest measured Fe$^{2+}$:Fe${^3+}$ ratio of 0.1 corresponding to the largest concentration of oxygen vacancies (δ = 0.19). …
