Showing papers on "Magnetic structure published in 2021"

Field-induced topological Hall effect and double-fan spin structure with a c -axis component in the metallic kagome antiferromagnetic compound Y Mn 6 Sn 6

Abstract: Geometric frustration in the kagome lattice makes it a great host for the flat electronic band, nontrivial topological properties, and novel magnetism. Here, we use magnetotransport measurements to map out the field-temperature phase diagram of the centrosymmetric $\mathrm{Y}{\mathrm{Mn}}_{6}{\mathrm{Sn}}_{6}$ with a Mn kagome lattice and show that the system exhibits the topological Hall effect (THE) with an in-plane applied magnetic field around 240 K. In addition, our neutron diffraction results demonstrate that the observed THE cannot arise from a magnetic skyrmion lattice, but instead from an in-plane field-induced double-fan spin structure with $c$-axis components. This paper provides a platform to understand the influence of a field-induced novel magnetic structure on magnetoelectric response in topological kagome metals.

Chiral properties of the zero-field spiral state and field-induced magnetic phases of the itinerant kagome metal YMn 6 Sn 6

Abstract: Applying a magnetic field in the hexagonal plane of $\mathrm{Y}{\mathrm{Mn}}_{6}{\mathrm{Sn}}_{6}$ leads to a complex magnetic phase diagram of commensurate and incommensurate phases, one of which coexists with the topological Hall effect (THE) generated by a unique fluctuation-driven mechanism. Using unpolarized neutron diffraction, we report on the solved magnetic structure for two previously identified, but unknown, commensurate phases. These include a low-temperature, high-field fanlike phase and a room-temperature, low-field canted antiferromagnetic phase. An intermediate incommensurate phase between the fanlike and forced ferromagnetic phases is also identified as the last known phase of the in-plane field-temperature diagram. Additional characterization using synchrotron powder diffraction reveals extremely high-quality, single-phase crystals, which suggests that the presence of two incommensurate magnetic structures throughout much of the phase diagram is an intrinsic property of the system. Interestingly, polarized neutron diffraction shows that the centrosymmetric system hosts preferential chirality in the zero-field double-flat-spiral phase, which, along with the THE, is a topologically nontrivial characteristic.

Magnetic and electronic structures of antiferromagnetic topological material candidate EuMg2Bi2

Abstract: EuMg2Bi2 has been investigated to understand the electronic and magnetic behaviors as an antiferromagnetic (AFM) topological semimetal candidate. High-quality single crystals of EuMg2Bi2 were grown via a Bi flux and, subsequently, characterized to be consistent with the previously reported bulk magnetic and resistivity properties. A ferromagnetic interaction is indicated by the positive Curie–Weiss temperature obtained through fitting the bulk magnetic susceptibility data. The bulk resistivity measurements reveal an interesting electronic behavior that is potentially influenced by a competing antiferromagnetic and ferromagnetic interaction in and out of the ab plane. From the resulting refinement of the neutron diffraction data, EuMg2Bi2 was found to exhibit an A-type magnetic structure with Eu2+ moments ferromagnetically aligned in the plane and antiferromagnetically stacked between neighbor ferromagnetic Eu layers. The power law fitting magnetic ordering parameter below TN ∼ 8 K agrees with the 2D Heisenberg model, indicating a weak interlayer antiferromagnetic interaction. Considering the magnetic structure determined by neutron diffraction, the surface state calculation suggests that EuMg2Bi2 is an AFM topological insulator candidate. Linearly dispersed Dirac surface states were also observed in our angle-resolved photoemission spectroscopy measurements, consistent with the calculation.

Anomalous Hall and Nernst effects in ferrimagnetic Mn4N films: Possible interpretations and prospects for enhancement

Abstract: Ferrimagnetic Mn4N is a promising material for heat flux sensors, based on the anomalous Nernst effect (ANE), because of its sizeable uniaxial magnetic anisotropy (Ku) and low saturation magnetization (Ms). We experimentally and theoretically investigated the ANE and anomalous Hall effect in sputter-deposited Mn4N films. It was revealed that the observed negative anomalous Hall conductivity (σxy) could be explained by two different coexisting magnetic structures, that is, a dominant magnetic structure with high Ku, contaminated by another structure with negligible Ku, owing to an imperfect degree of order of N. The observed transverse thermoelectric power (SANE) of +0.5 μV/K at 300 K yielded a transverse thermoelectric coefficient (αxy) of +0.34 A/(m · K), which was smaller than the value predicted from the first-principles calculation. The interpretation for αxy based on the first-principles calculations led us to conclude that the realization of single magnetic structure with high Ku and optimal adjustment of the Fermi level are promising approaches to enhance SANE in Mn4N through the sign reversal of σxy and the enlargement of αxy up to a theoretical value of 1.77 A/(m · K).

Nanocrystalline Soft Magnetic Iron-Based Materials from Liquid State to Ready Product.

Abstract: The review is devoted to the analysis of physical processes occurring at different stages of production and application of nanocrystalline soft magnetic materials based on Fe–Si–B doped with various chemical elements. The temperature dependences of the kinematic viscosity showed that above a critical temperature, the viscosity of multicomponent melts at the cooling stage does not coincide with the viscosity at the heating stage. Above the critical temperature, the structure of the melt is more homogeneous, the amorphous precursor from such a melt has greater plasticity and enthalpy of crystallization and, after nanocrystallization, the material has a higher permeability. The most effective inhibitor elements are insoluble in α-Fe and form a smoothed peak of heat release during crystallization. On the other hand, the finest nanograins and the highest permeability are achieved at a narrow high-temperature peak of heat release. The cluster magnetic structure of a nanocrystalline material is the cause of magnetic inhomogeneity, which affects the shape of the magnetic hysteresis loop and core losses.

Butterfly-shaped magnetoresistance in van der Waals ferromagnet Fe5GeTe2

Abstract: We have performed magnetoresistance (MR) measurements on van der Waals ferromagnetic devices using quenched- (Q-) and nonquenched- (NQ-) Fe5GeTe2 crystals A clear butterfly-shaped hysteresis has been observed for thin-film (less than 6 unit-cell layer) Q- and NQ-Fe5GeTe2 devices, but not for thicker film ones The switching field of the butterfly-shaped MR is consistent with the coercive filed obtained from the Hall measurements The MR ratio of the butterfly peak reaches about 10% at maximum, which is much larger than that observed with conventional magnetic materials Such a large MR ratio would be related to magnetic fluctuations due to the complicated magnetic structure in this material

Berry Phase Engineering in SrRuO3/SrIrO3/SrTiO3 Superlattices Induced by Band Structure Reconstruction.

Abstract: The Berry phase, which reveals the intimate geometrical structure underlying quantum mechanics, plays a central role in the anomalous Hall effect. In this work, we observed a sign change of Berry curvatures at the interface between the ferromagnet SrRuO3 (SRO) layer and the SrIrO3 (SIO) layer with strong spin-orbit coupling. The negative Berry curvature at the interface, induced by the strongly spin-orbit-coupled Ir 5d bands near the Fermi level, makes the SRO/SIO interface different from the SRO layer that has a positive Berry curvature. These opposite Berry curvatures led to two anomalous Hall effect (AHE) channels with opposite signs at the SRO/SIO interface and in the SRO layer, respectively, resulting in a hump-like feature in the Hall resistivity loop. This observation offers a straightforward explanation of the hump-like feature that is usually associated with the chiral magnetic structure or magnetic skyrmions. Hence, this study provides evidence to oppose the widely accepted claim that magnetic skyrmions induce the hump-like feature.

High-Pressure Neutron Diffraction Study of the Crystal and Magnetic Structure of Materials at the Pulsed Reactor IBR-2: Current Opportunities and Prospects

Abstract: The experimental capabilities and results of recent studies of the crystal and magnetic structure of functional materials on the diffractometers DN-12 and DN-6 of upgraded high-flux pulsed reactor IBR-2 in wide ranges of high pressures and temperatures are reviewed. The combination of high neutron flux on a sample, wide-aperture multidetector systems, and focusing devices has made it possible to implement diffraction experiments on samples with record-low volumes under ultrahigh pressures (up to 35 GPa) in the temperature range of 5–300 K. The results of recent studies of the structural and magnetic phase transitions in ferroelectrics, multiferroics, low-dimensional magnets, and other materials are presented.

Strong Coupling of Magnetism and Lattice Induces Near-Zero Thermal Expansion over Broad Temperature Windows in ErFe10V2−xMox Compounds

Abstract: Alloys with low thermal expansion could overcome thermal stress issues under temperature-fluctuated conditions and possess important application prospects, while they are restricted to finite chemi...

Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation

Abstract: The iron-chalcogenide high temperature superconductor Fe(Se,Te) (FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which may lead to novel superconducting phenomena. However, the recent studies have so far been largely concentrated on its band and spin structures while its mesoscopic electronic and magnetic response, crucial for future device applications, has not been explored experimentally. Here, we used scanning superconducting quantum interference device microscopy for its sensitivity to both local diamagnetic susceptibility and current distribution in order to image the superfluid density and supercurrent in FST. We found that in FST with 10% interstitial Fe, whose magnetic structure was heavily disrupted, bulk superconductivity was significantly suppressed whereas edge still preserved strong superconducting diamagnetism. The edge dominantly carried supercurrent despite of a very long magnetic penetration depth. The temperature dependences of the superfluid density and supercurrent distribution were distinctively different between the edge and the bulk. Our Heisenberg modeling showed that magnetic dopants stabilize anti-ferromagnetic spin correlation along the edge, which may contribute towards its robust superconductivity. Our observations hold implication for FST as potential platforms for topological quantum computation and superconducting spintronics.

Distinguishing antiferromagnetic spin sublattices via the spin Seebeck effect

Abstract: Determining the magnetic structure of antiferromagnets is a fundamental challenge for the basic understanding and development of antiferromagnetic spintronic devices. However, apart from techniques that probe individual spins in antiferromagnets directly (such as spin-polarized scanning tunneling microscopy), there are few techniques that can provide independent information for each antiferromagnetic sublattice. Here, the authors demonstrate that spin Seebeck signals from the antiferromagnetic insulator Cr${}_{2}$O${}_{3}$ are controlled by surface spins, and independently detect the orientation of the two different sublattices purely electrically.

Magnetic structure, mechanical stability and thermoelectric properties of VTiRhZ (Z = Si, Ge, Sn) quaternary Heusler alloys: first-principles calculations

Abstract: The magnetic structure, mechanical stability, and thermoelectric properties of quaternary VTiRhZ (Z = Si, Ge, Sn) Heusler alloys are investigated based on density functional theory (DFT). The calculations show that Y-type-I configuration is the most stable crystal structure for the studied alloys. The three alloys were found to have a half-metallic ferromagnetic structure with indirect band gaps in the majority spin channels of 0.42, 0.25, and 0.12 eV, for VTiRhSi, VTiRhGe, and VTiRhSn, respectively. They exhibit an appreciable total magnetic moment of 2 μB and a perfect spin-polarization of 100%, which are promising for future spintronic applications. The Seebeck coefficient (S), electrical conductivity (σ), and electronic thermal conductivity (κe) of VTiRhZ alloys were calculated using the semi-classical Boltzmann theory, whereas the lattice thermal conductivity (κL) was calculated using Slack’s equation. The calculations predict n-type VTiRhSi and VTiRhGe with figure of merit (ZT) values of 1.13 and 0.62 at 800 K, respectively, whereas VTiRhSn exhibits a p-type with a ZT value of 0.92, which is promising for future thermoelectric applications.

Crystallographic and magnetic structures of the V I 3 and LiV I 3 van der Waals compounds

Abstract: Two-dimensional (2D) layered magnetic materials are generating a great amount of interest for the next generation of electronic devices thanks to their remarkable properties associated with spin dynamics The recently discovered layered $\mathrm{V}{\mathrm{I}}_{3}$ ferromagnetic phase belongs to this family, although a full understanding of its properties is limited by the incomplete understanding of its crystallographic structure The motivation of this work is to address this issue Here, we investigate the $\mathrm{V}{\mathrm{I}}_{3}$ crystal structures at low temperature using both synchrotron x-ray and neutron powder diffraction and provide structural models for the two structural transitions occurring at 76 and 32 K Moreover, we confirm by magnetic measurements that $\mathrm{V}{\mathrm{I}}_{3}$ becomes ferromagnetic at 50 K and we question the establishment of a long-range magnetic structure by neutron diffraction We equally determined the magnetic properties of our recently reported $\mathrm{LiV}{\mathrm{I}}_{3}$ phase, which is like the well-known $\mathrm{Cr}{\mathrm{I}}_{3}$ ferromagnetic phase in terms of electronic and crystallographic structures and found an antiferromagnetic behavior with a N\'eel temperature of 12 K Such a finding provides extra clues for a better understanding of magnetism in these low-dimension compounds Finally, the easiness of preparing Li-based 2D magnetic materials by chemical/electrochemical means opens wide the opportunity to design materials with exotic properties

Field-tuned magnetic structure and phase diagram of the honeycomb magnet YbCl$_3$

Abstract: We report thermodynamic and neutron diffraction measurements on the magnetic ordering properties of the honeycomb lattice magnet YbCl$_3$. We find YbCl$_3$ exhibits a Neel type long-range magnetic order at the wavevector (0, 0, 0) below T$_N$ = 600 mK. This magnetic order is associated with a small sharp peak in heat capacity and most magnetic entropy release occurs above the magnetic ordering temperature. The magnetic moment lies in-plane, parallel to the monoclinic a -axis, whose magnitude m $_{\\text{Yb}}$ = 0.86(3) $\\mu$$_\\text{B}$ is considerably smaller than the expected fully ordered moment of2.24 $\\mu$$_\\text{B}$ for the doublet crystal-field ground state. The magnetic ordering moment gradually increases with increasing magnetic field perpendicular to the $ab$-plane, reaching a maximum value of 1.6(2) $\\mu$$_\\text{B}$ at 4 T, before it is completely suppressed above $\\sim9$ T.These results indicate the presence of strong quantum fluctuations in YbCl$_3$.

((R)-(-)-3-Hydroxyquinuclidium)[FeCl4]; a plastic hybrid compound with chirality, ferroelectricity and long range magnetic ordering

Abstract: Quinuclidinium salts and their derivatives are now in the focus of materials science as building units of multifunctional materials. Their properties can be easily switchable, allowing their use in a wide range of physical applications. One type of these kinds of materials, the homochiral hybrid halometallate ferroelectric compounds, is not well understood. In this work, (R)-(−)-3-quinuclidinol hydrochloride was used in the synthesis of ((R)-(−)-3-hydroxyquinuclidium)[FeCl4]. The use of this enantiomeric cation forces crystallographic non-centrosymmetry, which was confirmed by polarimetry and circular dichroism spectroscopy. We studied the physical properties of this compound at different temperatures by single crystal, synchrotron and neutron powder X-ray diffraction, which showed a rich series of structural and magnetic phase transitions. From synchrotron powder X-ray diffraction data, a plastic phase was observed above 370 K (phase I). Between 370 K and ca. 310 K, an intermediate polar phase was detected, solved in a non-centrosymmetric polar space group (C2) (phase II). Below ca. 310 K, the compound crystallizes in the triclinic P1 non-centrosymmetric space group (phase III) which is maintained down to 4 K, followed by phase IV, which shows tridimensional magnetic ordering. The temperature evolution of the neutron diffraction data shows the appearance of new reflections below 4 K. These reflections can be indexed to a commensurate propagation vector k = (0, 0, ½). The magnetic structure below TN was solved in the Ps1 Shubnikov space group, which gives rise to an antiferromagnetic structure, compatible with the magnetometry measurements. Near room temperature, the crystal phase transition is associated with a dielectric change. In particular, the phase transition between phase III (S.G.:P1) and phase II (S.G.:C2) involves an increase of symmetry between two non-centrosymmetric space groups. Therefore, it allows, by symmetry, the emergence of ferroelectric and ferroelastic ordering. Piezoresponse force microscopy (PFM) imaging measurements provided evidence for polarization switching and a local ferroelectric behavior of phase III at room temperature. Additionally, the obtained butterfly curve and hysteresis loop by PFM exhibits a low coercive voltage of ∼10 V. This value is remarkable, since it approaches those obtained for materials with application in ferroelectric random access memories (FeRAMs).

Noncollinear Magnetic Order in Two-Dimensional NiBr2 Films Grown on Au(111).

Abstract: Metal halides are a class of layered materials with promising electronic and magnetic properties persisting down to the two-dimensional limit. While most recent studies focused on the trihalide components of this family, the rather unexplored metal dihalides are also van der Waals layered systems with distinctive magnetic properties. Here we show that the dihalide NiBr2 grows epitaxially on a Au(111) substrate and exhibits semiconducting and magnetic behavior starting from a single layer. Through a combination of a low-temperature scanning-tunneling microscopy, low-energy electron diffraction, X-ray photoelectron spectroscopy, and photoemission electron microscopy, we identify two competing layer structures of NiBr2 coexisting at the interface and a stoichiometrically pure layer-by-layer growth beyond. Interestingly, X-ray absorption spectroscopy measurements revealed a magnetically ordered state below 27 K with in-plane magnetic anisotropy and zero-remanence in the single layer of NiBr2/Au(111), which we attribute to a noncollinear magnetic structure. The combination of such two-dimensional magnetic order with the semiconducting behavior down to the 2D limit offers the attractive perspective of using these films as ultrathin crystalline barriers in tunneling junctions and low-dimensional devices.

Strain dependence of Berry-phase-induced anomalous Hall effect in the non-collinear antiferromagnet Mn3NiN

Abstract: The anomalous Hall effect (AHE) has been shown to be present in certain non-collinear antiferromagnets due to their symmetry-breaking magnetic structure, and its magnitude is dependent primarily on the non-zero components of the Berry curvature. In the non-collinear antiferromagnet Mn3NiN, the Berry phase contribution has been predicted to have strong strain dependence, although in practice, direct observation may be obscured by other strain-related influences—for instance, magnetic phase transitions mediated by strain. To unravel the various contributions, we examine the thickness and temperature dependence of the AHE for films grown on the piezoelectric substrate BaTiO3. We observe a systematic reduction in TN due to increased compressive strain as film thickness is reduced and a linear decrease in the AHE magnitude as the films are cooled from their ferrimagnetic phase above TN to their antiferromagnetic phase below. At 190 K, we applied an electric field across a 0.5 mm thick BaTiO3 substrate with a 50 nm thick Mn3NiN film grown on top and we demonstrate that at the coercive field of the piezoelectric substrate, the tensile in-plane strain is estimated to be of the order of 0.15%, producing a 20% change in AHE. Furthermore, we show that this change is, indeed, dominated by the intrinsic strain dependence of the Berry curvature.

Stripe antiferromagnetic ground state of the ideal triangular lattice compound KErSe 2

Abstract: Rare-earth triangular lattice materials have been proposed as a good platform for the investigation of frustrated magnetic ground states. ${\mathrm{KErSe}}_{2}$, with the delafossite structure, contains perfect two-dimensional ${\mathrm{Er}}^{3+}$ triangular layers separated by potassium ions, realizing this ideal configuration and inviting study. Here we investigate the magnetism of ${\mathrm{KErSe}}_{2}$ at millikelvin temperatures by heat capacity and neutron powder diffraction. Heat capacity results reveal a magnetic transition at 0.2 K in zero applied field. This long-range order is suppressed by an applied magnetic field of 0.5 T below 0.08 K. Neutron powder diffraction suggests that the zero-field magnetic structure orders with $k=(\frac{1}{2},0,\frac{1}{2})$ in a stripe spin structure. Unexpectedly, Er is found to have a reduced moment of 3.06(1)${\ensuremath{\mu}}_{B}$/Er in the ordered state, and diffuse magnetic scattering, which originates at higher temperatures, is found to persist in the ordered state, potentially indicating magnetic fluctuations. Neutron diffraction collected under an applied field shows a metamagnetic transition at $\ensuremath{\sim}0.5$ T to ferromagnetic order with $k=(0,0,0)$ and two possible structures, which are likely dependent on the applied field direction. The zero-field stripe spin structure can be explained by the anisotropic interactions or the first-, second-, and third-neighbor couplings in the antiferromagnetic triangular lattice.

Magnetocaloric effect of high-entropy rare-earth alloy GdTbHoErY

Abstract: Magnetocaloric effect of a single-phase high-entropy rare-earth alloy GdTbHoErY with the hexagonal close-packed (HCP) structure was studied As the external field increases, the peak isothermal magnetic entropy change (ΔSM) of the alloy is accompanied by a hump, which widens the ΔSM peak and thus increases the refrigerant capacity (RC) value Under a magnetic field of 5 T, the RC and the ΔSM reach 453 J kg−1 and 54 J kg−1 K−1, respectively The high RC for the high-entropy alloy is mainly attributed to the wider working temperature range Moreover, the random distribution of atoms in the lattice leads to a complex magnetic structure and exchange coupling in this alloy This feature of high-entropy alloy GdTbHoErY makes a gradual change in the magnetic sequence, which leads to an enhanced magnetocaloric effect

Magnetic and electronic structure of the topological semimetal YbMnSb$_2$

Abstract: The antiferromagnetic (AFM) semimetal YbMnSb$_2$ has recently been identified as a candidate topological material, driven by time-reversal symmetry breaking. Depending on the ordered arrangement of Mn spins below the Neel temperature, $T_\mathrm{N}$ = 345 K, the electronic bands near the Fermi energy can ether have a Dirac node, a Weyl node or a nodal line. We have investigated the ground state magnetic structure of YbMnSb$_2$ using unpolarized and polarized single crystal neutron diffraction. We find that the Mn moments lie along the $c$ axis of the $P4/nmm$ space group and are arranged in a C-type AFM structure, which implies the existence of gapped Dirac nodes near the Fermi level. The results highlight how different magnetic structures can critically affect the topological nature of fermions in semimetals.

Perpendicular magnetic anisotropy at the Fe/Au(111) interface studied by Mössbauer, x-ray absorption, and photoemission spectroscopies

Abstract: The origin of the interfacial perpendicular magnetic anisotropy (PMA) induced in the ultrathin Fe layer on the Au(111) surface was examined using synchrotron-radiation-based M\"ossbauer spectroscopy (MS), x-ray magnetic circular dichroism (XMCD), and angle-resolved photoemission spectroscopy (ARPES). To probe the detailed interfacial electronic structure of orbital hybridization between the Fe $3d$ and Au $6p$ bands, we detected the interfacial proximity effect, which modulates the valence-band electronic structure of Fe, resulting in PMA. MS and XMCD measurements were used to detect the interfacial magnetic structure and anisotropy in orbital magnetic moments, respectively. In situ ARPES also confirms the initial growth of Fe on large spin-orbit coupled surface Shockley states under Au(111) modulated electronic states in the vicinity of the Fermi level. This suggests that PMA in the Fe/Au(111) interface originates from the cooperation effects among the spin, orbital magnetic moments in Fe, and large spin-orbit coupling in Au. These findings pave the way to develop interfacial PMA using $p\text{\ensuremath{-}}d$ hybridization with a large spin-orbit interaction.

Coherent spin rotation-induced zero thermal expansion in MnCoSi-based spiral magnets

Abstract: Materials exhibiting zero thermal expansion (ZTE), namely, volume invariance with temperature change, can resist thermal shock and are highly desired in modern industries for high-precision components. However, pure ZTE materials are rare, especially those that are metallic. Here, we report the discovery of a pure metallic ZTE material: an orthorhombic Mn1-xNixCoSi spiral magnet. The introduction of Ni can efficiently enhance the ferromagnetic exchange interaction and construct the transition from a spiral magnetic state to a ferromagnetic-like state in MnCoSi-based alloys. Systematic in situ neutron powder diffraction revealed a new cycloidal spiral magnetic structure in the bc plane in the ground state, which transformed to a helical spiral in the ab plane with increasing temperature. Combined with Lorentz transmission electron microscopy techniques, the cycloidal and helical spin order coherently rotated at varying periods along the c-axis during the magnetic transition. This spin rotation drove the continuous movement of the coupled crystalline lattice and induced a large negative thermal expansion along the a-axis, eventually leading to a wide-temperature ZTE effect. Our work not only introduces a new ZTE alloy but also presents a new mechanism by which to discover or design ZTE magnets. The introduction of minimal Ni into MnCoSi efficiently changes the magnetic interaction and establish a thermal-induced magnetic transition from a spiral magnetic state to a ferromagnetic-like state in Mn1-xNixCoSi alloys. With increasing the temperature, both the cycloidal and helical magnetic spin rotates continuously and coherently towards to b axis during the transition. Therefore, a wide-temperature range zero thermal expansion behaviour is realized owing to the robust magnetoelastic coupling.

Structural disorder and magnetic correlations driven by oxygen doping in Nd2NiO4+d (d ~ 0.11)

Abstract: We investigated the influence of oxygen over-stoichiometry on apical oxygen disorder and magnetic correlations in Nd2NiO4+d (d~0.11) in the temperature range of 2-300 K by means of synchrotron x-ray powder diffraction, neutron single crystal and powder diffraction studies, combined with macroscopic magnetic measurements. In the investigated temperature range, the compound crystalizes in a tetragonal commensurate structure with the P42/ncm space group with excess oxygen atoms occupy the 4b (3/4 1/4 1/4) interstitial sites, coordinated by four apical oxygen atoms. Large and anisotropic thermal displacement parameters are found for equatorial and apical oxygen atoms, which are strongly reduced on an absolute scale compared to the Nd2NiO4.23 phase. Maximum Entropy analysis of the neutron single crystal diffraction data uncovered anharmonic contributions to the displacement parameters of the apical oxygen atoms, toward the nearest vacant 4b interstitial site, related to the phonon assisted oxygen diffusion mechanism. Macroscopic magnetization measurements and neutron powder diffraction studies reveal long-range antiferromagnetic ordering of the Ni-sublattice at TN ~ 53 K with a weak ferromagnetic component along the c-axis, while the long-range magnetic ordering of the Nd-sublattice occurs below 10 K. Temperature dependent neutron diffraction patterns show the appearance of a commensurate magnetic order at TN with the propagation vector k = (100) and the emergence of an additional incommensurate phase below 30 K, while both phases coexist at 2 K. The commensurate magnetic structure is best described by the P42/nc`m` Shubnikov space group. Refined magnetic moments of the Ni and Nd-sites at 2 K are 1.144(76) muB and 1.632(52) muB respectively. A possible origin of the incommensurate phase is discussed and a tentative magnetic phase diagram is proposed.