Direct Observation of Large Amplitude Spin Excitations Localized in a Spin-Transfer Nanocontact

We report the direct observation of large amplitude spin-excitations localized in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments were conducted using a nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element resolved x-ray magnetic circular dichroism images show an abrupt onset of spin excitations at a threshold current that are localized beneath the nanocontact, with average spin precession cone angles of 25{\deg} at the contact center. The results strongly suggest that we have observed a localized magnetic soliton.Comment: 5 pages, 3 figure

X-Ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu

We have used a MHz lock-in x-ray spectro-microscopy technique to directly detect changes of magnetic moments in Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x-rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of $3\times 10^{-5}$ $\mu_\mathrm{B}$ on Cu atoms within the bulk of the 28 nm thick Cu film due to spin-accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments on Cu interface atoms are transiently increased by about 10% or $4\times 10^{-3}$ $\mu_\mathrm{B}$. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow

Direct observation and imaging of a spin-wave soliton with p−p-like symmetry

The prediction and realization of magnetic excitations driven by electrical currents via the spin transfer torque effect, enables novel magnetic nano-devices where spin-waves can be used to process and store information. The functional control of such devices relies on understanding the properties of non-linear spin-wave excitations. It has been demonstrated that spin waves can show both an itinerant character, but also appear as localized solitons. So far, it was assumed that localized solitons have essentially cylindrical, $s-$like symmetry. Using a newly developed high-sensitivity time-resolved magnetic x-ray microscopy, we instead observe the emergence of a novel localized soliton excitation with a nodal line, i.e. with $p-$like symmetry. Micromagnetic simulations identify the physical mechanism that controls the transition from $s-$ to $p-$like solitons. Our results suggest a potential new pathway to design artificial atoms with tunable dynamical states using nanoscale magnetic devices

Safety and efficacy of topical tranexamic acid over intravenous tranexamic acid in reducing blood loss and transfusion rates in hip and knee arthroplasty

Background: Tranexamic acid (TXA) is increasingly used in orthopedic surgery to reduce blood loss. Hence the present study was undertaken to compare the efficacy of topical TXA and intravenous (IV) TXA in reducing blood loss and transfusion rate in primary total hip and total knee arthroplasty.Methods: Total of 31 cases undergoing either primary THA (23 cases) or TKA (8 cases) during a study period from June were enrolled. Outcome measures were drained output, transfusion rate, drop in haemoglobin (Hb) and blood loss measured by Nadler et al formula.Results: In THR group, 12 (52.17%) cases and in TKA group, 3 (37.5%) cases were managed using IV TXA whereas 11 (47.82%) and 5 (62.5%) cases were managed using topical TXA in THR and TKR group respectively. The mean drain output was greater among IV TKR group (261.66±129.60 ml) as compared to topical TKR group (210±129.49 ml). In THR drain output in IV group was 216±104.08 ml. In both the groups, mean blood loss was lower in cases where IV TXA was administered as compared to topical TXA, (p>0.05). The mean drop in Hb was greater after topical administration of TXA in both the groups as compared to IV administered TXA. In THR group, 9 (39.13%) patients required blood transfusion. In sickle cell disease patients, we found more blood loss and drain output as compared to non-sickle cell disease (SCD) patients.Conclusions: Both IV and topical TXA are clinically effective and safe in decreasing calculated blood loss, Hb drop after THA and TKA.