Spin-Momentum Locking and Ultrafast Spin-Charge Conversion in Ultrathin Epitaxial Bi1 - x Sbx Topological Insulator.

The helicity of three-dimensional (3D) topological insulator surface states has drawn significant attention in spintronics owing to spin-momentum locking where the carriers' spin is oriented perpendicular to their momentum. This property can provide an efficient method to convert charge currents into spin currents, and vice-versa, through the Rashba-Edelstein effect. However, experimental signatures of these surface states to the spin-charge conversion are extremely difficult to disentangle from bulk state contributions. Here, spin- and angle-resolved photo-emission spectroscopy, and time-resolved THz emission spectroscopy are combined to categorically demonstrate that spin-charge conversion arises mainly from the surface state in Bi1 - x Sbx ultrathin films, down to few nanometers where confinement effects emerge. This large conversion efficiency is correlated, typically at the level of the bulk spin Hall effect from heavy metals, to the complex Fermi surface obtained from theoretical calculations of the inverse Rashba-Edelstein response. Both surface state robustness and sizeable conversion efficiency in epitaxial Bi1 - x Sbx thin films bring new perspectives for ultra-low power magnetic random-access memories and broadband THz generation.

Comparison of Exeter stem offset size for total hip arthroplasty between males and females: A retrospective series of 780 hips.

Background: Many orthopaedic surgeons use a 'standard' stem offset length, typically 37.5 mm and 44 mm for females and males respectively, in total hip arthroplasty. With increasingly personalized surgery, 'standard' one-size-fits-all stem lengths may be outdated. This study aims to test whether pre-operative templating affects stem length choice and whether 'standard' stem sizes are therefore outdated. Methods: We performed a retrospective chart review of all total hip arthroplasty patients using Stryker's Exeter cemented femoral hip system in our centre between 2016 and 2020. Demographic and surgical data were collected. Data from surgeons who templated pre-operatively were compared to data from those who did not. Results: 780 patients were included (309 male, 471 female), average age 71.4 years (range 23-96). We found a significant difference between male and female offset lengths; more males had an offset length of 44 mm and more females had an offset length of 37.5 mm (p = 0.004). Among surgeons who did not template pre-operatively, 20.6% of female patients and 10.3% of male patients had other 'non-standard' offset lengths. Among surgeons who did template pre-operatively, the proportion of both female and male patients who had other 'non-standard' offset lengths was significantly higher (43.1% and 23.4%, respectively p < 0.05). Conclusions: The difference between templating and non-templating surgeons' stem choice revealed significant individual variability between males and females. 'Standard' offset lengths for males and females were still used in the majority of our cohort. However, with the emergence of mainstream robotic arthroplasty, we feel that pre-operative templating has become a minimum standard.

Rare case of a low energy traumatic anterior dislocation of the native hip.

Anterior dislocations of the native hip are rare injuries, and normally a result of high energy trauma such as road traffic accidents. Delays in reduction of over 12 hours have been shown to increase the risk of avascular necrosis to the head of the femur significantly. We report the case of an elderly man who sustained an anterior dislocation of his native hip following a fall. The case highlights that prompt appropriate management can lead to excellent clinical outcomes.

Unusual presentation of atraumatic insufficiency pelvic fractures unmasking pregnancy-related osteoporosis: A case report.

We describe the case of a young 27-year-old Caucasian female who presented in the third trimester of her first pregnancy with sudden and severe suprapubic and left-sided hip pain without history of trauma. She was eventually diagnosed with two insufficiency fractures of the pelvis. The underlying diagnosis was pregnancy-related osteoporosis. Her baby was delivered successfully at term, with an elective caesarean section. The diagnosis was eventually made using a magnetic resonance imaging scan. Pregnancy-related osteoporosis is relatively rare, and cases of patients presenting with insufficiency fractures of this condition are rarer still. Our case raises the importance of considering this diagnosis in females in the later stages of pregnancy, with severe sudden hip or pelvis pain. The patient gave informed written consent for the publication of this case.

A systematic review of anterior cruciate ligament primary repair rehabilitation.

BACKGROUND: Rehabilitation after surgery of the injured anterior cruciate ligament (ACL) is crucial for satisfactory outcomes. Many trials have investigated this process after ACL reconstruction. The treatment of acute ACL ruptures with a repair technique has recently regained interest, although very little information is available about appropriate rehabilitation for such patients. The objective of this review was to evaluate studies on rehabilitation following ACL repair. METHODS: A systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted for patients undergoing a rehabilitation programme after ACL repair. The review has been registered on the International Prospective Register of Systematic Reviews (PROSPERO, Registration number: CRD42020173450). Elements of rehabilitation care we included in our strategy are postoperative bracing, home-based rehabilitation, strengthening exercises, proprioception and neuromuscular training. We searched PubMed, CINAHL, EMBASE, and the Cochrane Library for randomised trials of any form investigating rehabilitation protocols after repair of the injured ACL. Two reviewers independently assessed eligibility of trials. RESULTS: No trials were included. Available literature of lower evidence was included for discussion. CONCLUSIONS: No information is available from randomised trials to indicate whether there is any difference between rehabilitation protocols for patients who have undergone primary ACL repair.

COVID-19 antibody tests: statistical implications.

The coronavirus disease 2019 (COVID-19) pandemic has had significant implications for society, with the introduction of restrictive social measures. Antibody tests provide a way of identifying patients who have been previously exposed to the virus and thus may have a degree of immunity. This is important in the development of public health policy, as local and national bodies seek to relax social restrictions in an attempt to mitigate the socioeconomic impact of the pandemic. This article explores the essential statistical concepts used to interpret the findings of diagnostic investigations, with examples illustrated using COVID-19 antibody tests.

Observation of Large Unidirectional Rashba Magnetoresistance in Ge(111).

Relating magnetotransport properties to specific spin textures at surfaces or interfaces is an intense field of research nowadays. Here, we investigate the variation of the electrical resistance of Ge(111) grown epitaxially on semi-insulating Si(111) under the application of an external magnetic field. We find a magnetoresistance term that is linear in current density j and magnetic field B, hence, odd in j and B, corresponding to a unidirectional magnetoresistance. At 15 K, for I=10 µA (or j=0.33 A m^{-1}) and B=1 T, it represents 0.5% of the zero field resistance, a much higher value compared to previous reports on unidirectional magnetoresistance (UMR). We ascribe the origin of this magnetoresistance to the interplay between the externally applied magnetic field and the pseudomagnetic field generated by the current applied in the spin-splitted subsurface states of Ge(111). This unidirectional magnetoresistance is independent of the current direction with respect to the Ge crystal axes. It progressively vanishes, either using a negative gate voltage due to carrier activation into the bulk (without spin-splitted bands), or by increasing the temperature due to the Rashba energy splitting of the subsurface states lower than ∼58k_{B}. We believe that UMR could be used as a powerful probe of the spin-orbit interaction in a wide range of materials.

New drug, new problem: do hip fracture patients taking NOACs experience delayed surgery, longer hospital stay, or poorer outcomes?

INTRODUCTION: Neck of femur fractures are common in the comorbid, often anticoagulated, elderly. Non-vitamin K antagonist oral anticoagulants (NOACs) may affect patient outcomes. We aimed to evaluate whether hip fracture patients admitted on warfarin or NOAC therapy were at risk of operative delay, prolonged length of stay, or increased mortality. METHODS: We collected data for 845 patients admitted to our centre between October 2014 and December 2016. Multivariable linear regression analysis was performed to test the association between warfarin and NOAC therapy on time to surgery and length of stay. Variables in the regression model were age, sex, admission AMTS, pre-fracture mobility, ASA score, fracture type, and operation type. Fisher's exact test was used to evaluate whether warfarin or NOAC therapy delayed surgery beyond 36 or 48 hours, or decreased 30-day, 6-month, or 12-month survival. RESULTS: Time to surgery was delayed in anticoagulated patients (p = 0.028). NOAC therapy was independently associated with increased time to surgery beyond 36 hours (p = 0.001), although not beyond 48 hours (p = 0.355), whereas warfarin therapy was not associated with either. Anticoagulation did not increase length of stay (p = 0.331). Warfarin therapy significantly reduced 30-day survival (p = 0.007), but NOAC therapy did not (p = 0.244). Neither warfarin nor NOAC therapy affected further survival. CONCLUSIONS: NOAC therapy delays time to surgery beyond the NHS England 'Best Practice Tariff' in hip fracture patients. We aim to prospectively investigate long-term outcomes. Without a NOAC antidote, policy must change to ensure time-appropriate surgery for patients on NOACs. Preoperative involvement of the haematology team is essential.

Brodie abscess of the femoral capital epiphysis in a 2-year-old child caused by Kingella kingae.

We report the case of a Brodie abscess of the femoral capital epiphysis from which Kingella kingae was isolated. This is to the best of our knowledge the first report of a Brodie abscess of the femoral capital epiphysis from which K. kingae was isolated.

Evidence for spin-to-charge conversion by Rashba coupling in metallic states at the Fe/Ge(111) interface.

The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect transistor. However, the spin Hall effect in bulk germanium is too weak to produce spin currents, whereas large Rashba effect at Ge(111) surfaces covered with heavy metals could generate spin-polarized currents. The Rashba spin splitting can actually be as large as hundreds of meV. Here we show a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generate very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. The presence of these metallic states at the Fe/Ge(111) interface is demonstrated by first-principles electronic structure calculations. By this, we demonstrate how to take advantage of the spin-orbit coupling for the development of the spin field-effect transistor.

Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces.

The spin-orbit interaction couples the electrons' motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism-the Rashba effect-in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.

Spin to Charge Conversion at Room Temperature by Spin Pumping into a New Type of Topological Insulator: α-Sn Films.

We present results on spin to charge current conversion in experiments of resonant spin pumping into the Dirac cone with helical spin polarization of the elemental topological insulator (TI) α-Sn. By angle-resolved photoelectron spectroscopy (ARPES), we first check that the Dirac cone (DC) at the α-Sn (0 0 1) surface subsists after covering Sn with Ag. Then we show that resonant spin pumping at room temperature from Fe through Ag into α-Sn layers induces a lateral charge current that can be ascribed to the inverse Edelstein effect by the DC states. Our observation of an inverse Edelstein effect length much longer than those generally found for Rashba interfaces demonstrates the potential of TIs for the conversion between spin and charge in spintronic devices. By comparing our results with data on the relaxation time of TI free surface states from time-resolved ARPES, we can anticipate the ultimate potential of the TI for spin to charge conversion and the conditions to reach it.

Spin transport in p-type germanium.

We report on the spin transport properties in p-doped germanium (Ge-p) using low temperature magnetoresistance measurements, electrical spin injection from a ferromagnetic metal and the spin pumping-inverse spin Hall effect method. Electrical spin injection is carried out using three-terminal measurements and the Hanle effect. In the 2-20 K temperature range, weak antilocalization and the Hanle effect provide the same spin lifetime in the germanium valence band (≈1 ps) in agreement with predicted values and previous optical measurements. These results, combined with dynamical spin injection by spin pumping and the inverse spin Hall effect, demonstrate successful spin accumulation in Ge. We also estimate the spin Hall angle θ(SHE) in Ge-p (6-7 x 10(-4) at room temperature, pointing out the essential role of ionized impurities in spin dependent scattering.

Additive interfacial chiral interaction in multilayers for stabilization of small individual skyrmions at room temperature.

Facing the ever-growing demand for data storage will most probably require a new paradigm. Nanoscale magnetic skyrmions are anticipated to solve this issue as they are arguably the smallest spin textures in magnetic thin films in nature. We designed cobalt-based multilayered thin films in which the cobalt layer is sandwiched between two heavy metals and so provides additive interfacial Dzyaloshinskii-Moriya interactions (DMIs), which reach a value close to 2 mJ m(-2) in the case of the Ir|Co|Pt asymmetric multilayers. Using a magnetization-sensitive scanning X-ray transmission microscopy technique, we imaged small magnetic domains at very low fields in these multilayers. The study of their behaviour in a perpendicular magnetic field allows us to conclude that they are actually magnetic skyrmions stabilized by the large DMI. This discovery of stable sub-100 nm individual skyrmions at room temperature in a technologically relevant material opens the way for device applications in the near future.

Cerebral involvement in IgG4-related disease.

IgG4-related disease is a recently recognised multi-system disease. Common organ involvement includes the pancreas, biliary tree and salivary glands. Central nervous system involvement has been infrequently reported. In a single-centre cohort of 84 patients, we report cerebral involvement in three (4%) patients. Details of cerebral involvement in these patients are outlined, including pituitary involvement in two patients and a diffuse autoimmune-like encephalopathy in the other.

Spin pumping and inverse spin Hall effect in platinum: the essential role of spin-memory loss at metallic interfaces.

Through combined ferromagnetic resonance, spin pumping, and inverse spin Hall effect experiments in Co|Pt bilayers and Co|Cu|Pt trilayers, we demonstrate consistent values of ℓsfPt=3.4±0.4 nm and θSHEPt=0.056±0.010 for the respective spin diffusion length and spin Hall angle for Pt. Our data and model emphasize the partial depolarization of the spin current at each interface due to spin-memory loss. Our model reconciles the previously published spin Hall angle values and explains the different scaling lengths for the ferromagnetic damping and the spin Hall effect induced voltage.

Towards electrical spin injection into LaAlO3-SrTiO3.

Future spintronics devices will be built from elemental blocks allowing the electrical injection, propagation, manipulation and detection of spin-based information. Owing to their remarkable multi-functional and strongly correlated character, oxide materials already provide such building blocks for charge-based devices such as ferroelectric field-effect transistors (FETs), as well as for spin-based two-terminal devices such as magnetic tunnel junctions, with giant responses in both cases. Until now, the lack of suitable channel materials and the uncertainty of spin-injection conditions in these compounds had however prevented the exploration of similar giant responses in oxide-based lateral spin transport structures. In this paper, we discuss the potential of oxide-based spin FETs and report magnetotransport data that suggest electrical spin injection into the LaAlO(3)-SrTiO(3) interface system. In a local, three-terminal measurement scheme, we analyse the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or longitudinal magnetic fields (Hanle and 'inverted' Hanle effects). The spin accumulation signal appears to be much larger than expected, probably owing to amplification effects by resonant tunnelling through localized states in the LaAlO(3). We give perspectives on how to achieve direct spin injection with increased detection efficiency, as well on the implementation of efficient top gating schemes for spin manipulation.

Crossover from spin accumulation into interface states to spin injection in the germanium conduction band.

Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. In this Letter, we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Ge. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from 200 K up to room temperature. In this regime, the spin signal is reduced to a value compatible with the spin diffusion model. More interestingly, the observation in this regime of inverse spin Hall effect in germanium generated by spin pumping and the modulation of the spin signal by a gate voltage clearly demonstrate spin accumulation in the germanium conduction band.