Antiferromagnetic interlayer exchange coupled Co68B32/Ir/Pt multilayers.

Synthetic antiferromagnetic structures can exhibit the advantages of high velocity similarly to antiferromagnets with the additional benefit of being imaged and read-out through techniques applied to ferromagnets. Here, we explore the potential and limits of synthetic antiferromagnets to uncover ways to harness their valuable properties for applications. Two synthetic antiferromagnetic systems have been engineered and systematically investigated to provide an informed basis for creating devices with maximum potential for data storage, logic devices, and skyrmion racetrack memories. The two systems considered are (system 1) CoB/Ir/Pt of N repetitions with Ir inducing the negative coupling between the ferromagnetic layers and (system 2) two ferromagnetically coupled multilayers of CoB/Ir/Pt, coupled together antiferromagnetically with an Ir layer. From the hysteresis, it is found that system 1 shows stable antiferromagnetic interlayer exchange coupling between each magnetic layer up to N = 7. Using Kerr imaging, the two ferromagnetic multilayers in system 2 are shown to undergo separate maze-like switches during hysteresis. Both systems are also studied as a function of temperature and show different behaviors. Micromagnetic simulations predict that in both systems the skyrmion Hall angle is suppressed with the skyrmion velocity five times higher in system 1 than system 2.

Manipulation of Magnetic Skyrmion Density in Continuous Ir/Co/Pt Multilayers.

We show that magnetic skyrmions can be stabilised at room temperature in continuous [Ir/Co/Pt]5 multilayers on SiO2/Si substrates without the prior application of electric current or magnetic field. While decreasing the Co thickness, a transition of the magnetic domain patterns from worm-like state to separated stripes is observed. The skyrmions are clearly imaged in both states using magnetic force microscopy. The density of skyrmions can be significantly enhanced after applying the "in-plane field procedure". Our results provide means to manipulate magnetic skyrmion density, further allowing for the optimised engineering of skyrmion-based devices.

Scanning Thermal Microscopy and Ballistic Phonon Transport in Lateral Spin Valves.

Using scanning thermal microscopy, we have mapped the spatial distribution of temperatures in an operating nanoscale device formed from a magnetic injector, an Ag connecting wire, and a magnetic detector. An analytical model explained the thermal diffusion over the measured temperature range (2-300 K) and injector-detector separation (400-3000 nm). The characteristic diffusion lengths of the Peltier and Joule heat differ remarkably below 60 K, a fact that can be explained by the onset of ballistic phonon heat transfer in the substrate.

Pt and CoB trilayer Josephson [Formula: see text] junctions with perpendicular magnetic anisotropy.

We report on the electrical transport properties of Nb based Josephson junctions with Pt/Co[Formula: see text]B[Formula: see text]/Pt ferromagnetic barriers. The barriers exhibit perpendicular magnetic anisotropy, which has the main advantage for potential applications over magnetisation in-plane systems of not affecting the Fraunhofer response of the junction. In addition, we report that there is no magnetic dead layer at the Pt/Co[Formula: see text]B[Formula: see text] interfaces, allowing us to study barriers with ultra-thin Co[Formula: see text]B[Formula: see text]. In the junctions, we observe that the magnitude of the critical current oscillates with increasing thickness of the Co[Formula: see text]B[Formula: see text] strong ferromagnetic alloy layer. The oscillations are attributed to the ground state phase difference across the junctions being modified from zero to [Formula: see text]. The multiple oscillations in the thickness range [Formula: see text] nm suggests that we have access to the first zero-[Formula: see text] and [Formula: see text]-zero phase transitions. Our results fuel the development of low-temperature memory devices based on ferromagnetic Josephson junctions.

Reversible spin storage in metal oxide-fullerene heterojunctions.

We show that hybrid MnOx/C60 heterojunctions can be used to design a storage device for spin-polarized charge: a spin capacitor. Hybridization at the carbon-metal oxide interface leads to spin-polarized charge trapping after an applied voltage or photocurrent. Strong electronic structure changes, including a 1-eV energy shift and spin polarization in the C60 lowest unoccupied molecular orbital, are then revealed by x-ray absorption spectroscopy, in agreement with density functional theory simulations. Muon spin spectroscopy measurements give further independent evidence of local spin ordering and magnetic moments optically/electronically stored at the heterojunctions. These spin-polarized states dissipate when shorting the electrodes. The spin storage decay time is controlled by magnetic ordering at the interface, leading to coherence times of seconds to hours even at room temperature.

Optical conversion of pure spin currents in hybrid molecular devices.

Carbon-based molecules offer unparalleled potential for THz and optical devices controlled by pure spin currents: a low-dissipation flow of electronic spins with no net charge displacement. However, the research so far has been focused on the electrical conversion of the spin imbalance, where molecular materials are used to mimic their crystalline counterparts. Here, we use spin currents to access the molecular dynamics and optical properties of a fullerene layer. The spin mixing conductance across Py/C60 interfaces is increased by 10% (5 × 1018 m-2) under optical irradiation. Measurements show up to a 30% higher light absorbance and a factor of 2 larger photoemission during spin pumping. We also observe a 0.15 THz slowdown and a narrowing of the vibrational peaks. The effects are attributed to changes in the non-radiative damping and energy transfer. This opens new research paths in hybrid magneto-molecular optoelectronics, and the optical detection of spin physics in these materials.Carbon-based molecules could prove useful in terahertz and optical devices controlled by pure spin currents. Here, conversely, the authors use spin currents to probe molecular dynamics and enhance the optical response of a fullerene layer, enabling hybrid magneto-molecular optoelectronic devices.

Interfacial Origin of the Magnetisation Suppression of Thin Film Yttrium Iron Garnet.

Yttrium iron garnet has a very high Verdet constant, is transparent in the infrared and is an insulating ferrimagnet leading to its use in optical and magneto-optical applications. Its high Q-factor has been exploited to make resonators and filters in microwave devices, but it also has the lowest magnetic damping of any known material. In this article we describe the structural and magnetic properties of single crystal thin-film YIG where the temperature dependence of the magnetisation reveals a decrease in the low temperature region. In order to understand this complex material we bring a large number of structural and magnetic techniques to bear on the same samples. Through a comprehensive analysis we show that at the substrate -YIG interface, an interdiffusion zone of only 4-6 nm exists. Due to the interdiffusion of Y from the YIG and Gd from the substrate, an addition magnetic layer is formed at the interface whose properties are crucially important in samples with a thickness of YIG less than 200 nm.

Emergent magnetism at transition-metal-nanocarbon interfaces.

Charge transfer at metallo-molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc-C60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo-carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp3 orbitals are annealed into sp2-π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz-π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices.

Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle.

We have investigated single electron spin transport in individual single crystal bcc Co30Fe70 nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 µs, a value much longer than previously reported.

Potential donor families' experiences of organ and tissue donation-related communication, processes and outcome.

We aimed to describe the experiences of families of potential organ and tissue donors eligible for donation after circulatory death or brain death. Forty-nine family members of potential donors from four Melbourne hospitals were interviewed to assess their experiences of communication, processes and the outcomes of donation. Interviews were recorded, transcribed verbatim and analysed thematically. Families expressed a range of perspectives on themes of communication, hospital processes and care, the processes of consent and donation and reflected on decisions and outcomes. They expressed satisfaction overall with communication when receiving bad news, discussing death and donation. Honest and frank communication and being kept up-to-date and prepared for potential outcomes were important aspects for families, especially those of post circulatory death donors. Participants reported high levels of trust in healthcare professionals and satisfaction with the level of care received. Many donor families indicated the process was lengthy and stressful, but not significantly enough to adversely affect their satisfaction with the outcome. Both the decision itself and knowing others' lives had been saved provided them with consolation. No consenting families, and only some non-consenting families, regretted their decisions. Many expressed they would benefit from a follow-up opportunity to ask questions and clarify possible misunderstandings. Overall, while experiences varied, Australian families valued frank communication, trusted health professionals, were satisfied with the care their family member received and with donation processes, despite some apparent difficulties. Family satisfaction, infrequently assessed, is an important outcome and these findings may assist education for Australian organ donation professionals.

Understanding Australian families' organ donation decisions.

Numbers of deceased organ donors in Australia have increased, but rates of consent to donation remain at around 60%. Increasing family consent is a key target for the Australian Organ and Tissue Authority. Reasons for donation decisions have been reported in the international literature, but little is known of reasons for Australian families' decisions. Potential organ donors in four Melbourne hospitals were identified and 49 participants from 40 families (23 consenting and 17 non-consenting) were interviewed to understand reasons for consent decisions. Themes for consent to organ donation included that: donation was consistent with the deceased's explicit wishes or known values, the desire to help others or self-including themes of altruism, pragmatism, preventing others from being in the same position, consolation received from donation and aspects of the donation conversation and care that led families to believe donation was right for them. Themes for non-consent included: lack of knowledge of wishes; social, cultural and religious beliefs; factors related to the donation process and family exhaustion; and conversation factors where negative events influenced decisions. While reasons for consent were similar to those described in international literature, reasons for non-consent differed in that there was little emphasis on lack of trust of the medical profession, concerns regarding level of care provided to the potential donor, preserving the deceased's body, fears of body invasion or organ allocation fairness.

Factors relating to consent for organ donation: prospective data on potential organ donors.

BACKGROUND: Obtaining family consent to organ donation is a significant obstacle to improving further Australian deceased organ donation rates. Currently, neither the consent rates for donors eligible to donate after circulatory death, nor factors that influence decision to decline or consent to donation in general are known in Australia. METHODS: This study at four university teaching hospitals in Melbourne, Victoria, examined consecutive patients where organ donation was discussed with the family RESULTS: A total of 123 cases were identified; the family consent rate was 52.8%, and 34.1% proceeded to donation. Consent to donation was related to potential donor factors such as country of birth, cultural background in Australia, a non-religious or Christian background and registration on the Australian Organ Donor Register. Family-related factors included being English speaking and having knowledge of the deceased's wishes about organ donation. Family of donation after circulatory death-eligible donors were less likely to consent to donation than the family of donation after brain death-eligible donors, although not reaching statistical significance. Among consented potential donors, those eligible for donation after brain death and with a shorter length of stay were more likely to proceed to donating organs for transplantation. CONCLUSION: Despite a small sample size, these findings describe current consent and donation rates and associated factors and may assist in improving conversations about organ donation.

Early experience of MAGEC magnetic growing rods in the treatment of early onset scoliosis.

PURPOSE: Magnetically controlled growing rod systems have been introduced over recent years as an alternative to traditional growing rods for management of early onset scoliosis. The purpose of this paper is to report our early experience of a magnetically controlled growing rod system (MAGEC, Ellipse). METHODS: Review of pre-operative, postoperative and follow-up Cobb angles and spinal growth in case series of eight patients with a minimum 23 months' follow-up (23-36 months). RESULTS: A total of six patients had dual rod constructs implanted and two patients received single-rod constructs. Four patients had MAGEC rods as a primary procedure. Four were revisions from other systems. Mean age at surgery in the primary group was 4.5 years (range 3.9-6.9). In patients who had MAGEC as a primary procedure, mean pre-operative Cobb angle was 74° (63-94), with postoperative Cobb angle of 42° (32-56) p ≤ 0.001 (43% correction). Mean Cobb angle at follow-up was 42° (35-50). Spinal growth rate was 6 mm/year. One sustained proximal screw pull out. A final patient sustained a rod fracture. Mean age at surgery in the revision group was 10.9 years (range 9-12.6). Mean pre-operative Cobb angle was 45° (34-69). Postoperative Cobb angle was 42° (33-63) (2% correction). Mean Cobb angle at follow-up was 44° (28-67). Mean spinal growth rate was 12 mm/year. Two patients developed loss of distraction. CONCLUSION: MAGEC growing rod system effectively controls early onset scoliosis when used as either a primary or revision procedure. Although implant-related complications are not uncommon, the avoidance of multiple surgeries following implantation is beneficial compared with traditional growing rod systems.

Donation after cardiac death: are Australian emergency clinicians supportive?

To improve organ donation processes and outcomes, many Australian hospitals have introduced donation after cardiac death (DCD) following the 2010 publication of the National Protocol for DCD. As emergency clinicians play a significant role in identifying potential DCD donors, it is critical to assess their support and knowledge. Although many support DCD, most are unaware of the protocol or procedures regarding DCD. Education is needed and desired by many emergency clinicians.

Review of Kinemax total knee replacements performed at the NHS treatment centre, Weston-Super-Mare: five-year results.

As part of the national initiative to reduce waiting times for joint replacement surgery in Wales, the Cardiff and Vale NHS Trust referred 224 patients to the NHS Treatment Centre in Weston-Super-Mare for total knee replacement (TKR). A total of 258 Kinemax TKRs were performed between November 2004 and August 2006. Of these, a total of 199 patients (232 TKRs, 90%) have been followed up for five years. This cohort was compared with 258 consecutive TKRs in 250 patients, performed at Cardiff and Vale Orthopaedic Centre (CAVOC) over a similar time period. The five year cumulative survival rate was 80.6% (95% confidence interval (CI) 74.0 to 86.0) in the Weston-Super-Mare cohort and 95.0% (95% CI 90.2 to 98.2) in the CAVOC cohort with revision for any reason as the endpoint. The relative risk for revision at Weston-Super-Mare compared with CAVOC was 3.88 (p < 0.001). For implants surviving five years, the mean Oxford knee scores (OKS) and mean EuroQol (EQ-5D) scores were similar (OKS: Weston-Super-Mare 29 (2 to 47) vs CAVOC 29.8 (3 to 48), p = 0.61; EQ-5D: Weston-Super-Mare 0.53 (-0.38 to 1.00) vs CAVOC 0.55 (-0.32 to 1.00), p = 0.79). Patients with revised TKRs had significantly lower Oxford knee and EQ-5D scores (p < 0.001). The results show a higher revision rate for patients operated at Weston-Super-Mare Treatment Centre, with a reduction in functional outcome and quality of life after revision. This further confirms that patients moved from one area to another for joint replacement surgery fare poorly.

Accuracy of the skyline view for detecting dorsal cortical penetration during volar distal radius fixation.

Fractures of the distal radius are commonly treated using volar locking plates. Several complications have been associated with this procedure, including extensor tendon irritation and rupture. It has been suggested that prominence of screws past the dorsal cortex may contribute to this complication. This study aimed to determine the ability of the skyline view to demonstrate screws penetrating the dorsal cortex. A volar locking plate was applied to a synthetic forearm model. Lateral, oblique, and skyline views were obtained, with the distal screws both beneath and 1 mm beyond the dorsal cortex. The images were shown to orthopaedic trainees who were asked to decide if screws penetrated the dorsal cortex. Subjects were correct in 83% of cases using the skyline view compared with 77% (p = 0.05, lateral) and 50% (p < 0.01, oblique). This study demonstrates the skyline view of the distal radius could be a useful and accurate addition to routine intraoperative fluoroscopy views.

Spatial fluctuations of loose spin coupling in CuMn/Co multilayers.

A detailed investigation of magnetic impurity-mediated interlayer exchange coupling observed in Cu(0.94)Mn(0.06)/Co multilayers using polarized neutron reflectometry and magnetic x-ray techniques is reported. Excellent descriptions of temperature and magnetic field dependent biquadratic coupling are obtained using a variant of the loose spin model that takes into account the distribution of the impurity Mn ions in three dimensions. Positional disorder of the magnetic impurities is shown to enhance biquadratic coupling via a new contribution J(2)(fluct), leading to a temperature dependent canting of magnetic domains in the multilayer. These results provide measurable effects on RKKY coupling associated with the distribution of impurities within planes parallel to the interfaces.

New directions in spintronics.

Conventional microelectronics exploits only the charge degree of freedom of the electron. Bringing the spin degree of freedom to bear on sensing, radio frequency, memory and logic applications opens up new possibilities for 'more than Moore' devices incorporating magnetic components that can couple to an external field, store a bit of data or represent a Boolean state. Moreover, the electron spin is an archetypal two-state quantum system that is an excellent candidate for a solid-state realization of a qubit.