Valence-state mixing and reduced magnetic moment inFe3-δGeTe2single crystals with varying Fe content probed by x-ray spectroscopy.

We present a spectroscopic study of the magnetic properties ofFe3-δGeTe2single crystals with varying Fe content, achieved by tuning the stoichiometry of the crystals. We carried out x-ray absorption spectroscopy and analyzed the x-ray circular magnetic dichroism spectra using the sum rules, to determine the orbital and spin magnetic moments of the materials. We find a clear reduction of the spin and orbital magnetic moment with increasing Fe deficiency. Magnetic susceptibility measurements show that the reduction in magnetization is accompanied by a reduced Curie temperature. Multiplet calculations reveal that the Fe2+state increasingly mixes with a higher valence state when the Fe deficiency is increased. This effect is correlated with the weakening of the magnetic moment. As single crystals are the base material for exfoliation processes, our results are relevant for the assembly of 2D magnetic heterostructures.

Adherence of the rotating vortex lattice in the noncentrosymmetric superconductor Ru7B3to the London model.

The noncentrosymmetric superconductor Ru7B3has in previous studies demonstrated remarkably unusual behaviour in its vortex lattice (VL), where the nearest neighbour directions of the vortices dissociate from the crystal lattice and instead show a complex field-history dependence, and the VL rotates as the field is changed. In this study, we look at the VL form factor of Ru7B3during this field-history dependence, to check for deviations from established models, such as the London model. We find that the data is well described by the anisotropic London model, which is in accordance with theoretical predictions that the alterations to the structure of the vortices due to broken inversion symmetry should be small. From this, we also extract values for the penetration depth and coherence length.

Giant valley-Zeeman coupling in the surface layer of an intercalated transition metal dichalcogenide.

Spin-valley locking is ubiquitous among transition metal dichalcogenides with local or global inversion asymmetry, in turn stabilizing properties such as Ising superconductivity, and opening routes towards 'valleytronics'. The underlying valley-spin splitting is set by spin-orbit coupling but can be tuned via the application of external magnetic fields or through proximity coupling. However, only modest changes have been realized to date. Here, we investigate the electronic structure of the V-intercalated transition metal dichalcogenide V1/3NbS2 using microscopic-area spatially resolved and angle-resolved photoemission spectroscopy. Our measurements and corresponding density functional theory calculations reveal that the bulk magnetic order induces a giant valley-selective Ising coupling exceeding 50 meV in the surface NbS2 layer, equivalent to application of a ~250 T magnetic field. This energy scale is of comparable magnitude to the intrinsic spin-orbit splittings, and indicates how coupling of local magnetic moments to itinerant states of a transition metal dichalcogenide monolayer provides a powerful route to controlling their valley-spin splittings.

Toggle-like current-induced Bloch point dynamics of 3D skyrmion strings in a room temperature nanowire.

Research into practical applications of magnetic skyrmions, nanoscale solitons with interesting topological and transport properties, has traditionally focused on two dimensional (2D) thin-film systems. However, the recent observation of novel three dimensional (3D) skyrmion-like structures, such as hopfions, skyrmion strings (SkS), skyrmion bundles, and skyrmion braids, motivates the investigation of new designs, aiming to exploit the third spatial dimension for more compact and higher performance spintronic devices in 3D or curvilinear geometries. A crucial requirement of such device schemes is the control of the 3D magnetic structures via charge or spin currents, which has yet to be experimentally observed. In this work, we utilise real-space imaging to investigate the dynamics of a 3D SkS within a nanowire of Co8Zn9Mn3 at room temperature. Utilising single current pulses, we demonstrate current-induced nucleation of a single SkS, and a toggle-like positional switching of an individual Bloch point at the end of a SkS. The observations highlight the possibility to locally manipulate 3D topological spin textures, opening up a range of design concepts for future 3D spintronic devices.

Omega Flap Technique: Revisiting Conventional Wisdom.

Various surgical techniques have been described for the release of syndactylized fingers. In our experience, the omega flap technique, which includes a dorsal truncated flap and an anchor incision on the volar side, stands out as a good technique to release syndactyly. Incidentally, in symbrachydactyly also, the fused digits can be released using this technique. Despite this, we could find no reference in the recent years. We would like to stress the ease and importance of this technique, hoping many practicing hand surgeons will benefit from this. Our purpose was to revisit this technique and expose it to the younger generation of hand surgeons. We have operated on 20 cases of syndactyly of different types-simple, compound, and complex-and 5 cases of symbrachydactyly. In all cases, the omega flap on the dorsum and anchor incision on the volar aspect of the finger forming 2 lateral palmar flaps were used. The release of syndactyly was satisfactory in all patients. There was no flap necrosis. None of these cases have required secondary surgery because the primary releases were adequate. Release of syndactyly had been a problem for centuries. Awareness of the disability was insufficient in earlier days; currently, they seek early medical care. The release should be complete. These children must be able to achieve the form and function of the hand, and additionally precision to work. We believe that the use of omega flap and anchor flap is a good procedure for syndactyly release.

Spin Dynamics and Unconventional Coulomb Phase in Nd_{2}Zr_{2}O_{7}.

We investigate the temperature dependence of the spin dynamics in the pyrochlore magnet Nd_{2}Zr_{2}O_{7} by neutron scattering experiments. At low temperature, this material undergoes a transition towards an "all-in-all-out" antiferromagnetic phase and the spin dynamics encompass a dispersionless mode, characterized by a dynamical spin ice structure factor. Unexpectedly, this mode is found to survive above T_{N}≈300 mK. Concomitantly, elastic correlations of the spin ice type develop. These are the signatures of a peculiar correlated paramagnetic phase which can be considered as a new example of Coulomb phase. Our observations near T_{N} do not reproduce the signatures expected for a Higgs transition, but show reminiscent features of the "all-in-all-out" order superimposed on a Coulomb phase.

Chiral singlet superconductivity in the weakly correlated metal LaPt3P.

Chiral superconductors are novel topological materials with finite angular momentum Cooper pairs circulating around a unique chiral axis, thereby spontaneously breaking time-reversal symmetry. They are rather scarce and usually feature triplet pairing: a canonical example is the chiral p-wave state realized in the A-phase of superfluid He3. Chiral triplet superconductors are, however, topologically fragile with the corresponding gapless boundary modes only weakly protected against symmetry-preserving perturbations in contrast to their singlet counterparts. Using muon spin relaxation measurements, here we report that the weakly correlated pnictide compound LaPt3P has the two key features of a chiral superconductor: spontaneous magnetic fields inside the superconducting state indicating broken time-reversal symmetry and low temperature linear behaviour in the superfluid density indicating line nodes in the order parameter. Using symmetry analysis, first principles band structure calculation and mean-field theory, we unambiguously establish that the superconducting ground state of LaPt3P is a chiral d-wave singlet.

Deriving the skyrmion Hall angle from skyrmion lattice dynamics.

Magnetic skyrmions are topologically non-trivial, swirling magnetization textures that form lattices in helimagnetic materials. These magnetic nanoparticles show promise as high efficiency next-generation information carriers, with dynamics that are governed by their topology. Among the many unusual properties of skyrmions is the tendency of their direction of motion to deviate from that of a driving force; the angle by which they diverge is a materials constant, known as the skyrmion Hall angle. In magnetic multilayer systems, where skyrmions often appear individually, not arranging themselves in a lattice, this deflection angle can be easily measured by tracing the real space motion of individual skyrmions. Here we describe a reciprocal space technique which can be used to determine the skyrmion Hall angle in the skyrmion lattice state, leveraging the properties of the skyrmion lattice under a shear drive. We demonstrate this procedure to yield a quantitative measurement of the skyrmion Hall angle in the room-temperature skyrmion system FeGe, shearing the skyrmion lattice with the magnetic field gradient generated by a single turn Oersted wire.

Investigation of the magnetic ground state of GaV4S8using powder neutron diffraction.

The magnetic ground state of polycrystalline Néel skyrmion hosting material GaV4S8has been investigated usingacsusceptibility and powder neutron diffraction. In the absence of an applied magnetic field GaV4S8undergoes a transition from a paramagnetic to a cycloidal state below 13 K and then to a ferromagnetic-like state below 6 K. With evidence fromacsusceptibility and powder neutron diffraction, we have identified the commensurate magnetic structure at 1.5 K, with ordered magnetic moments of 0.23(2) µBon the V1 sites and 0.22(1) µBon the V2 sites. These moments have ferromagnetic-like alignment but with a 39(8)° canting of the magnetic moments on the V2 sites away from the V4cluster. In the incommensurate magnetic phase that exists between 6 and 13 K, we provide a thorough and careful analysis of the cycloidal magnetic structure exhibited by this material using powder neutron diffraction.

Strain relaxation dynamics of multiferroic orthorhombic manganites.

Resonant ultrasound spectroscopy has been used to characterise strain coupling and relaxation behavior associated with magnetic/magnetoelectric phase transitions in GdMnO3, TbMnO3and TbMn0.98Fe0.02O3through their influence on elastic/anelastic properties. Acoustic attenuation ahead of the paramagnetic to colinear-sinusoidal incommensurate antiferromagnetic transition at ∼41 K correlates with anomalies in dielectric properties and is interpreted in terms of Debye-like freezing processes. A loss peak at ∼150 K is related to a steep increase in electrical conductivity with a polaron mechanism. The activation energy,Ea, of ≳0.04 eV from a loss peak at ∼80 K is consistent with the existence of a well-defined temperature interval in which the paramagnetic structure is stabilised by local, dynamic correlations of electric and magnetic polarisation that couple with strain and have relaxation times in the vicinity of ∼10-6s. Comparison with previously published data for Sm0.6Y0.4MnO3confirms that this pattern may be typical for multiferroic orthorhombicRMnO3perovskites (R= Gd, Tb, Dy). A frequency-dependent loss peak near 10 K observed for TbMnO3and TbMn0.98Fe0.02O3, but not for GdMnO3, yieldedEa⩾ ∼0.002 eV and is interpreted as freezing of some magnetoelastic component of the cycloid structure. Small anomalies in elastic properties associated with the incommensurate and cycloidal magnetic transitions confirm results from thermal expansion data that the magnetic order parameters have weak but significant coupling with strain. Even at strain magnitudes of ∼0.1-1‰, polaron-like strain effects are clearly important in defining the development and evolution of magnetoelectric properties in these materials. Strains associated with the cubic-orthorhombic transition due to the combined Jahn-Teller/octahedral tilting transition in the vicinity of 1500 K are 2-3 orders of magnitude greater. It is inevitable that ferroelastic twin walls due to this transition would have significantly different magnetoelectric properties from homogeneous domains due to magnetoelastic coupling with steep strain gradients.

Real-space imaging of confined magnetic skyrmion tubes.

Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures. While they are commonly portrayed as two dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the host material. The study of this skyrmion tube state (SkT) is vital for furthering the understanding of skyrmion formation and dynamics for future applications. However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure. The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigation into this unexplored dimension of the skyrmion spin texture.

Restoration of Five Digit Hand in Type III B & C Thumb Hypoplasia-A Game Changer in Surgical Management.

Background Hypoplasia of thumb is the second common congenital difference of the thumb, next only to duplication. It may occur as an isolated hand difference or as a part of radial longitudinal deficiency. In approximately 60% of these children, the radius shows hypoplasia. The incidence of thumb hypoplasia is one in 100,000 live births. In 50% of these children, the other hand will also have similar deficiency, although variable in severity. Hypoplasia of thumb has been classified into five major categories, according to the increasing severity of hypoplasia. Type III hypoplasia of thumb is characterized by skeletal hypoplasia involving the first metacarpal and carpometacarpal joint, absent intrinsic muscles and rudimentary extrinsic muscles. It was further subclassified into types A, B & C. Type III B, described by Manske and McCarroll, involves extensive deficiency of extrinsic and intrinsic musculature with aplasia of the metacarpal base. Type III C, described by Buck-Gramcko, has hypoplastic metacarpal head. Methods It is widely believed that reconstruction of Type III B & C hypoplastic thumb will not be functionally useful, and they are often included in the indications for pollicization in thumb hypoplasia. In India, we frequently come across parents, who are not willing to remove the hypoplastic digit. This forced us to find out a way to reconstruct the hypoplastic thumb into a functionally useful digit. We describe our surgical technique of reconstruction of hypoplastic thumbs and our experience in utilization of the technique in five children with Type III B & C hypoplasia of thumb. Carpometacarpal joint of thumb was reconstructed and stabilized with a toe phalangeal transfer in the first stage and an opponensplasty was done in the second stage to improve movement. Results In all the five operated children, our surgical technique yielded a stable thumb which was functional. The donor site morbidity was acceptable. The parents were satisfied with the appearance and functional improvement. Conclusion Surgical reconstruction of hypoplastic thumbs of Type III B & C is possible, and conversion of these poorly developed remnants into a useful digit by our surgical technique is a gamechanger in the management of thumb hypoplasia.

Superconductivity and the upper critical field in the chiral noncentrosymmetric superconductor NbRh2B2.

NbRh2B2 crystallises in a chiral noncentrosymmetric structure and exhibits bulk type-II superconductivity below [Formula: see text] K. Here we show that the temperature dependence of the upper critical field deviates from the behaviour expected for both Werthamer-Helfand-Hohenberg and the Ginzburg-Landau models and that [Formula: see text] T exceeds the Pauli paramagnetic limit, [Formula: see text] T. We explore the reasons for this enhancement. Transverse-field muon spectroscopy measurements suggest that the superconducting gap is either s-wave or [Formula: see text]-wave, and the pressure dependence of [Formula: see text] reveals the superconducting gap is primarily s-wave in character. The magnetic penetration depth [Formula: see text] nm. Heat capacity measurements reveal the presence of a multigap [Formula: see text]-wave superconducting order parameter and moderate electron-phonon coupling.

Nuclear spin assisted quantum tunnelling of magnetic monopoles in spin ice.

Extensive work on single molecule magnets has identified a fundamental mode of relaxation arising from the nuclear-spin assisted quantum tunnelling of nearly independent and quasi-classical magnetic dipoles. Here we show that nuclear-spin assisted quantum tunnelling can also control the dynamics of purely emergent excitations: magnetic monopoles in spin ice. Our low temperature experiments were conducted on canonical spin ice materials with a broad range of nuclear spin values. By measuring the magnetic relaxation, or monopole current, we demonstrate strong evidence that dynamical coupling with the hyperfine fields bring the electronic spins associated with magnetic monopoles to resonance, allowing the monopoles to hop and transport magnetic charge. Our result shows how the coupling of electronic spins with nuclear spins may be used to control the monopole current. It broadens the relevance of the assisted quantum tunnelling mechanism from single molecular spins to emergent excitations in a strongly correlated system.

Evidence for dynamic kagome ice.

The search for two-dimensional quantum spin liquids, exotic magnetic states remaining disordered down to zero temperature, has been a great challenge in frustrated magnetism over the last few decades. Recently, evidence for fractionalized excitations, called spinons, emerging from these states has been observed in kagome and triangular antiferromagnets. In contrast, quantum ferromagnetic spin liquids in two dimensions, namely quantum kagome ices, have been less investigated, yet their classical counterparts exhibit amazing properties, magnetic monopole crystals as well as magnetic fragmentation. Here, we show that applying a magnetic field to the pyrochlore oxide Nd2Zr2O7, which has been shown to develop three-dimensional quantum magnetic fragmentation in zero field, results in a dimensional reduction, creating a dynamic kagome ice state: the spin excitation spectrum determined by neutron scattering encompasses a flat mode with a six arm shape akin to the kagome ice structure factor, from which dispersive branches emerge.

Pauling Entropy, Metastability, and Equilibrium in Dy_{2}Ti_{2}O_{7} Spin Ice.

Determining the fate of the Pauling entropy in the classical spin ice material Dy_{2}Ti_{2}O_{7} with respect to the third law of thermodynamics has become an important test case for understanding the existence and stability of ice-rule states in general. The standard model of spin ice-the dipolar spin ice model-predicts an ordering transition at T≈0.15 K, but recent experiments by Pomaranski et al. suggest an entropy recovery over long timescales at temperatures as high as 0.5 K, much too high to be compatible with the theory. Using neutron scattering and specific heat measurements at low temperatures and with long timescales (0.35 K/10^{6} s and 0.5 K/10^{5} s, respectively) on several isotopically enriched samples, we find no evidence of a reduction of ice-rule correlations or spin entropy. High-resolution simulations of the neutron structure factor show that the spin correlations remain well described by the dipolar spin ice model at all temperatures. Furthermore, by careful consideration of hyperfine contributions, we conclude that the original entropy measurements of Ramirez et al. are, after all, essentially correct: The short-time relaxation method used in that study gives a reasonably accurate estimate of the equilibrium spin ice entropy due to a cancellation of contributions.

Magnetisation process in the rare earth tetraborides, NdB4 and HoB4.

A field-induced magnetisation process in the frustrated antiferromagnets is often much richer compared to the materials without competing interactions. The applied field tends to stabilise unusual spin configurations which frequently results in the appearance of magnetisation plateaux. Here we report a study into the field-induced magnetisation of the two frustrated rare earth tetraborides, HoB4 and NdB4. NdB4 shows a fractional magnetisation plateau occurring at M/M sat ≈ [Formula: see text] before saturating in a field of 33 kOe. On cooling down to 0.5 K the temperature dependent susceptibility of NdB4 shows an unconventional transition where the system returns to the zero field antiferromagnetic state from a higher-temperature ferrimagnetic state. We are able to reconstruct the magnetic phase diagram of NdB4 from the magnetisation, susceptibility and resistivity measurements for both H [Formula: see text] c and H ⊥ c. For HoB4, the most interesting behaviour is found at the lowest temperature of 0.5 K, where the field dependent magnetisation demonstrates a new fractional [Formula: see text]-magnetisation plateau. Further insight into the relations between the exchange interactions and single ion effects is gained through high-field magnetisation measurements in both HoB4 and NdB4.

Time-Reversal Symmetry Breaking in Re-Based Superconductors.

To trace the origin of time-reversal symmetry breaking (TRSB) in Re-based superconductors, we performed comparative muon-spin rotation and relaxation (µSR) studies of superconducting noncentrosymmetric Re_{0.82}Nb_{0.18} (T_{c}=8.8 K) and centrosymmetric Re (T_{c}=2.7 K). In Re_{0.82}Nb_{0.18}, the low-temperature superfluid density and the electronic specific heat evidence a fully gapped superconducting state, whose enhanced gap magnitude and specific-heat discontinuity suggest a moderately strong electron-phonon coupling. In both Re_{0.82}Nb_{0.18} and pure Re, the spontaneous magnetic fields revealed by zero-field µSR below T_{c} indicate time-reversal symmetry breaking and thus unconventional superconductivity. The concomitant occurrence of TRSB in centrosymmetric Re and noncentrosymmetric ReT (T=transition metal), yet its preservation in the isostructural noncentrosymmetric superconductors Mg_{10}Ir_{19}B_{16} and Nb_{0.5}Os_{0.5}, strongly suggests that the local electronic structure of Re is crucial for understanding the TRSB superconducting state in Re and ReT. We discuss the superconducting order parameter symmetries that are compatible with the experimental observations.

Signatures of the Kondo effect in VSe2.

VSe2 is a transition metal dichaclogenide which has a charge- density wave transition that has been well studied. We report on a low-temperature upturn in the resistivity and, at temperatures below this resistivity minimum, an unusual magnetoresistance which is negative at low fields and positive at higher fields, in single crystals of VSe2. The negative magnetoresistance has a parabolic dependence on the magnetic field and shows little angular dependence. The magnetoresistance at temperatures above the resistivity minimum is always positive. We interpret these results as signatures of the Kondo effect in VSe2. An upturn in the susceptibility indicates the presence of interlayer V ions which can provide the localized magnetic moments required for scattering the conduction electrons in the Kondo effect. The low-temperature behaviour of the heat capacity, including a high value of γ, along with a deviation from a Curie-Weiss law observed in the low-temperature magnetic susceptibility, are consistent with the presence of magnetic interactions between the paramagnetic interlayer V ions and a Kondo screening of these V moments.

Spin-valley locking in the normal state of a transition-metal dichalcogenide superconductor.

Metallic transition-metal dichalcogenides (TMDCs) are benchmark systems for studying and controlling intertwined electronic orders in solids, with superconductivity developing from a charge-density wave state. The interplay between such phases is thought to play a critical role in the unconventional superconductivity of cuprates, Fe-based and heavy-fermion systems, yet even for the more moderately-correlated TMDCs, their nature and origins have proved controversial. Here, we study a prototypical example, 2H-NbSe2, by spin- and angle-resolved photoemission and first-principles theory. We find that the normal state, from which its hallmark collective phases emerge, is characterized by quasiparticles whose spin is locked to their valley pseudospin. This results from a combination of strong spin-orbit interactions and local inversion symmetry breaking, while interlayer coupling further drives a rich three-dimensional momentum dependence of the underlying Fermi-surface spin texture. These findings necessitate a re-investigation of the nature of charge order and superconducting pairing in NbSe2 and related TMDCs.