We present measurements of the planar Nernst effect (PNE) and the planar Hall effect (PHE) of nickel-iron (Ni-Fe) alloy thin films. We suspend the thin-film samples, measurement leads, and lithographically-defined heaters and thermometers on silicon-nitride membranes to greatly simplify control and measurement of thermal gradients essential to quantitative determination of magnetothermoelectric effects. Since these thermal isolation structures allow measurements of longitudinal thermopower, or the Seebeck coefficient, and four-wire electrical resistivity of the same thin film, we can quantitatively demonstrate the link between the longitudinal and transverse effects as a function of applied in-plane field and angle. Finite element thermal analysis of this essentially 2D structure allows more confident determination of the thermal gradient, which is reduced from the simplest assumptions due to the particular geometry of the membranes, which are more than 350 μm wide in order to maximize sensitivity to transverse thermoelectric effects. The resulting maximum values of the PNE and PHE coefficients for the Ni-Fe film with 80% Ni we study here are α PNE,max = 30 nV K −1 and ρ PHE,max = 2 nΩ m, respectively. All signals are exclusively sin 2θ symmetry with applied field, ruling out longdistance spin transport effects. We also consider a Mott-like relation between the PNE and PHE, and use both this and the standard Mott relation to determine the energy-derivative of the resistivity at the Fermi energy to be ∂ρ/∂E = 4.7 × 10 −7 Ω m eV −1 , which is very similar to values for films we previously measured using similar thermal platforms. Finally, using an estimated value for the lead contribution to the longitudinal thermopower, we show that the anisotropic magnetoresistance (AMR) ratio in this Ni-Fe film is two times larger than the magnetothermopower ratio, which is the first evidence of a deviation from strict adherence to the Mott relation between Seebeck coefficient and resistivity.

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Metallic non-local spin valves (NLSVs) are important in modern spintronics due to their ability to separate pure spin current from charge current. These metallic nanostructures, often constructed from features with widths in the deep sub-micron regime, generate significant thermal gradients in operation, and the heat generated has important consequences for spin injection and transport. We use e-beam nanolithography to manufacture NLSVs with Ni-Fe alloy ferromagnetic nanowires and aluminum spin channels on 500 nm silicon nitride (Si-N) membranes in order to lower the thermal conductance of the substrate dramatically. While this extreme example of thermal engineering in a spintronic system increases the background non-local signals in ways expected based on earlier work, it also enhances thermoelectric effects, including the anomalous Nernst effect and reveals a previously unknown thermally-assisted electrical spin injection that results from a purely in-plane thermal gradient. We examine these effects as a function of temperature and, by careful comparison with 2D finite element models of the thermal gradients calculated at a single temperature, demonstrate that the anomalous Nernst coefficient of the 35 nm thick Ni-Fe alloy, R N = 0.17 at T = 200 K, is in line with the few previous measurements of this effect for thin films.

The anomalous Nernst effect, which generates an out-of-plane charge voltage in response to a thermal gradient perpendicular to the magnetization of a ferromagnet, can play a significant role in many spintronic devices where large thermal gradients exist. Since they typically include features deep within the submicron regime, nonlocal spin valves can be made very sensitive to this effect by lowering the substrate thermal conductance. Here, we use nonlocal spin valves suspended on thin silicon nitride membranes to determine the temperature dependence of the anomalous Nernst coefficient of 35 nm thick permalloy (Ni80Fe20) from 78 K to 300 K. In a device with a simple ferromagnet geometry, the transverse Seebeck coefficient shows a weak temperature dependence, with values at all T near 2.5 μV/K. Assuming previously measured values of the Seebeck coefficient for permalloy, which has a near-linear dependence on T, leads to a low temperature upturn in the anomalous Nernst coefficient RN. We also show that the temperature dependence of this coefficient is different when a constricted nanowire is used as the ferromagnetic detector element.

Results from the STREAM stage 1 trial showed that a 9-month regimen for patients with rifampicin-resistant tuberculosis was non-inferior to the 20-month regimen recommended by the 2011 WHO treatment guidelines. Similar levels of severe adverse events were reported on both regimens suggesting the need for further research to optimise treatment. Stage 2 of STREAM evaluates two additional short-course regimens, both of which include bedaquiline. Throughout stage 2 of STREAM, new drug choices and a rapidly changing treatment landscape have necessitated changes to the trial’s design to ensure it remains ethical and relevant. This paper describes changes to the trial design to ensure that stage 2 continues to answer important questions. These changes include the early closure to recruitment of two trial arms and an adjustment to the definition of the primary endpoint. If the STREAM experimental regimens are shown to be non-inferior or superior to the stage 1 study regimen, this would represent an important contribution to evidence about potentially more tolerable and more efficacious MDR-TB regimens, and a welcome advance for patients with rifampicin-resistant tuberculosis and tuberculosis control programmes globally.Trial registration: ISRCTN ISRCTN18148631. Registered 10 February 2016