Low Field Conditions Research Articles

Compositional accuracy in atom probe tomography analyses performed on III-N light emitting diodes

Laser-assisted atom probe tomography (APT) and high-resolution dark-field electron holography (HR-DFEH) were performed to investigate the composition of a polar [0001] GaN/AlxGa1 − xN/InyGa1 − yN light emitting diode. In particular, the III-site fraction of both AlxGa1 − xN and InyGa1 − yN alloys was studied adopting a comparative approach. HR-DFEH allows mapping the projected strain with a subnanometer spatial resolution which is used for the calculation of the two-dimensional alloy composition distribution. APT provides three-dimensional alloys composition distribution with a nanometer spatial resolution. However, here we reveal that important inaccuracies affect local composition measurements. A Ga-poor composition is obtained in high DC-electric field regions. Moreover, such inaccuracies may be locally enhanced where the [0001] pole intersects the surface of the analyzed specimen, leading to a lower fraction of Ga measured. III-site fractions closer to the nominal values were measured at low field conditions. Ga loss is thought to be due to preferential DC field induced evaporation of Ga ions between laser pulses. This is explained in terms of formation of a metallic layer on the tip surface during APT analysis, where weak Ga-Ga bonds are formed, promoting the loss of Ga at high field conditions.

Simulation of the Impact of Ionized Impurity Scattering on the Total Mobility in Si Nanowire Transistors.

Nanowire transistors (NWTs) are being considered as possible candidates for replacing FinFETs, especially for CMOS scaling beyond the 5-nm node, due to their better electrostatic integrity. Hence, there is an urgent need to develop reliable simulation methods to provide deeper insight into NWTs’ physics and operation, and unlock the devices’ technological potential. One simulation approach that delivers reliable mobility values at low-field near-equilibrium conditions is the combination of the quantum confinement effects with the semi-classical Boltzmann transport equation, solved within the relaxation time approximation adopting the Kubo–Greenwood (KG) formalism, as implemented in this work. We consider the most relevant scattering mechanisms governing intraband and multi-subband transitions in NWTs, including phonon, surface roughness and ionized impurity scattering, whose rates have been calculated directly from the Fermi’s Golden rule. In this paper, we couple multi-slice Poisson–Schrödinger solutions to the KG method to analyze the impact of various scattering mechanisms on the mobility of small diameter nanowire transistors. As demonstrated here, phonon and surface roughness scattering are strong mobility-limiting mechanisms in NWTs. However, scattering from ionized impurities has proved to be another important mobility-limiting mechanism, being mandatory for inclusion when simulating realistic and doped nanostructures, due to the short range Coulomb interaction with the carriers. We also illustrate the impact of the nanowire geometry, highlighting the advantage of using circular over square cross section shapes.

Flexible IGZO TFTs and Their Suitability for Space Applications

In this paper, low earth orbit radiation (LEO), temperature, and magnetic field conditions are mimicked to investigate the suitability of flexible InGaZnO transistors for lightweight space wearables. More specifically, the impacts of high energetic electron irradiation with fluences up to $10^{12}\,\,{\mathrm{ e}}^{-}$ /cm2, low operating temperatures down to 78 K and magnetic fields up to 11 mT are investigated. This simulates 278 h in LEO. The threshold voltage and mobility of transistors that were exposed to $e^{-}$ irradiation are found to shift by +(0.09 ± 0.05) V and $-(0.6\pm 0.5)\,\,{\mathrm{ cm}}^{2}{\mathrm{ V}}^{-1}{\mathrm{ s}}^{-1}$ . Subsequent low temperature exposure resulted in additional shifts of +0.38 V and $-5.95\,\,{\mathrm{ cm}}^{2}{\mathrm{ V}}^{-1}{\mathrm{ s}}^{-1}$ for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. Conversely, the performance of the devices was observed not to be significantly affected by the magnetic fields. Finally, a Cascode amplifier presenting a voltage gain of 10.3 dB and a cutoff frequency of 1.2 kHz is demonstrated after the sample had been irradiated, cooled down, and exposed to the magnetic fields. If these notions are considered during the systems design, these devices can be used to unobtrusively integrate sensor systems into space suits.

Explicit Model of Channel Charge, Backscattering, and Mobility for Graphene FET in Quasi-Ballistic Regime

Ballistic (collision free) and drift-diffusive (collision dominated) transport mechanisms are both present in graphene, and they together contribute in the current conduction in a graphene FET (GFET). In this paper, we propose an analytical drain current model based on ballistic ( ${n}_{B}$ ) and drift-diffusive ( ${n}_{D}$ ) charge densities, backscattering coefficient ( ${R}$ ), and quasi-ballistic mobility ( $\mu _{\text {eff}}$ ). ${n}_{B}$ is calculated using the McKelvey flux theory and ${n}_{D}$ using the surface potential approach. A closed-form analytical expression is derived for the backscattering coefficient, which is valid under both low and high electric field conditions. The effective quasi-ballistic mobility is obtained by considering both scattering-dominated and scattering free mobilities. The proposed model is well aligned with experimental data, in all regions of operation, for single- and double-gate GFETs.

Proteomic analysis and microtubule dynamicity of human sperm in electromagnetic cryopreservation.

The proteomic changes, microtubule dynamicity, and quality parameters of human sperm were investigated during cryopreservation in an extremely low electromagnetic field (ELEF) condition. Semen samples were obtained from 210 healthy individuals with normospermia and then were divided into three experimental groups: fresh control, frozen control, and frozen ELEF group. Shotgun proteomics was performed to assess the identification of microtubule proteins of the sperm in experimental groups. Microtubule dynamicity, secondary, and tertiary structure modifications of tubulins, characteristics of transmission electron microscopy of sperm as well as sperm quality parameters were evaluated. The expression ratios of α- and β-tubulins were significantly increased after cryopreservation compared with fresh control while this ratio was not significantly different in frozen ELEF group. The expression ratio of tubulin polymerization-promoting protein was significantly decreased after cryopreservation compared with fresh control. The length, width, and the activity of microtubule, secondary, and tertiary structures of tubulins, motility, and the viability of the sperm were decreased in frozen control as compared with fresh control. The microtubule activity, secondary, and tertiary structures of sperm tubulin in frozen ELEF group were higher than frozen control. Transmission electron microscopy of microtubules showed that the size of the width and length of the microtubules in frozen ELEF group were greater than frozen control. Motility, viability, and reactive oxygen species levels were improved in frozen ELEF group when compared with frozen control. While the microtubule dynamicity of the sperm was affected by the cryopreservation, this trait was improved during the electromagnetic cryopreservation resulted in better motility and viability.

Composition Metrology of Ternary Semiconductor Alloys Analyzed by Atom Probe Tomography

Ternary semiconductor alloys based on the AyB1–yC stoichiometry are widely employed in electronic devices, and their composition plays a key role in band gap engineering of heterostructures. We have studied the crucial issue of accuracy in composition measurements of AlyGa1–yN and MgyZn1–yO alloys using atom probe tomography (APT). The results indicate a similar behavior for both nitride and oxide systems. A correct site fraction y is measured at low field conditions, while Ga and Zn preferentially evaporate at high field, yielding an overestimation of y. Furthermore, APT data sets exhibit local biases depending on the distribution of the electrostatic field at the specimen surface. We estimate the detection efficiencies for each species and interpret the results through a model describing preferential evaporation in simple terms.

Strain Characteristics of Ic in Brass-Laminated GdBCO CC Tape Under Tension at Various Low Temperature and Magnetic Field Conditions

Transport properties of coated conductor tapes can be affected by stress and strain induced during fabrication, cool-down, and operation. Therefore, it is important to understand the strain/stress dependence of the critical current of the coated conductor tapes in the reversible region under magnetic field considering practical applications such as magnets and coils. In this paper, the strain characteristics of critical current, I c , in high temperature superconducting (HTS)-coated conductor tapes fabricated using reactive co-evaporation by deposition and reaction reinforced with brass-foil laminate were investigated under external magnetic field at various cryogenic temperatures while applying uniaxial tension. Results show that I c dependences on magnetic field and temperature were similar between brass-laminated coated conductor and Cu-stabilized tape. The irreversible strain limit and the irreversible stress limit of brass-laminated coated conductor tape increased as temperature decreased from 77 to 20 K. This behavior resulted from thermal hardening of the coated conductor tape at low temperature.

Evaluation of a Biostimulant (Pepton) Based in Enzymatic Hydrolyzed Animal Protein in Comparison to Seaweed Extracts on Root Development, Vegetative Growth, Flowering, and Yield of Gold Cherry Tomatoes Grown under Low Stress Ambient Field Conditions.

The objectives of this experiment were to determine the effects of different application rates of an enzyme hydrolyzed animal protein biostimulant (Pepton) compared to a standard application rate of a biostimulant derived from seaweed extract (Acadian) on plant growth parameters and yield of gold cherry tomatoes (Solanum lycopersicum L.). Biostimulant treatments were applied starting at 15 days after transplant and every 2 weeks thereafter for a total of 5 applications. One treatment group received no biostimulant (Control). Three treatment groups (Pepton-2, Pepton-3, Pepton-4) received Pepton at different application rates equivalent to 2, 3, or 4 kg/ha applied by foliar (first 2 applications) and by irrigation (last 3 applications). Another treatment group (Acadian) received Acadian at 1.5 L/ha by irrigation for all five applications. All groups received the regular fertilizer application for this crop at transplantation, flowering, and fruiting periods. There were four plots per treatment group. Each plot had a surface area of 21 m2 that consisted of two rows that were 7 m long and 1.5 m wide. Plant height, stem diameter, distance from head to bouquet flowering, fruit set distance between the entire cluster and cluster flowering fruit set, leaf length, and number of leaves per plant was recorded for 20 plants (5 plants per plot) at 56 and 61 days after the first application. Root length and diameter of cherry tomatoes were determined at harvest from 20 randomly selected plants. Harvesting yield per plot was registered and production per hectare was calculated. Both biostimulants improved (P < 0.05) all vegetative parameters compared with the control group. There was a positive linear (P < 0.001) effect of Pepton application rate for all parameters. The calculated yield was 7.8 and 1 Ton/ha greater that represent 27 and 2.9% higher production for Pepton applied at 4 kg/ha compared to the control and to Acadian, respectively. In conclusion, Pepton was effective improving yield of gold cherry tomatoes under the low stress ambient growing conditions of this experiment. Probably short-chain peptides present in Pepton are involved in endogenous hormones and metabolic mediators that could explain the results obtained in this study.

Field-Dependent Measurement of GaAs Composition by Atom Probe Tomography.

The composition of GaAs measured by laser-assisted atom probe tomography may be inaccurate depending on the experimental conditions. In this work, we assess the role of the DC field and the impinging laser energy on such compositional bias. The DC field is found to have a major influence, while the laser energy has a weaker one within the range of parameters explored. The atomic fraction of Ga may vary from 0.55 at low-field conditions to 0.35 at high field. These results have been interpreted in terms of preferential evaporation of Ga at high field. The deficit of As is most likely explained by the formation of neutral As complexes either by direct ejection from the tip surface or upon the dissociation of large clusters. The study of multiple detection events supports this interpretation.

Backward-Wave Oscillator Operating in Low Magnetic Fields Using a Hybrid-TE11 Mode

We present the design of a backward-wave oscillator based on a novel slow-wave structure (SWS) operating under low magnetic field conditions (<0.2 T). The design features a high-power electron beam interacting in dual synchronism with TM01 and hybrid TE11 modes. By exploiting mode control techniques, low magnetic fields with asymmetrical beam trajectories, a dominant interaction with the higher frequency hybrid TE11 mode is established. We present a design of the full interaction circuit, which also features a compact mode converter and an output coupler to produce a TE01 mode at the dual rectangular waveguide output. Simulations with a high-frequency structural simulator demonstrate dual-mode backward wave synchronism. A quantitative analysis of the electric field profiles is also presented. We also use a particle-in-cell (PIC) solver to predict the SWS performance under hot-test facility specific conditions. Using a 490-kV, 84-A electron beam under a guiding magnetic field of 0.15 T, PIC simulations predict an output power of 18 MW at 5 GHz with a peak power efficiency of 44%.

Polarization of Soft Materials through Magnetic Alignment of Polymeric Organogels under Low-Field Conditions

Through application of an external magnetic field upon jellification of poly(3-hydroxybutyric acid-co-3-hydroxyvaleric) acid (PHBV) polymer in different solvents, an anisotropic organogel is obtained. This material presents two alignment steps in an external magnetic field, in the liquid phase and during the jellification, both phenomena measured by magnetic field induced linear birefringence. Remarkably, the organogel developed in this study presents a strong level of birefringence, 80% of its maximum, in an external magnetic field as low as 2 T resulting from the magnetic alignment of the fibers of the material. This anisotropic material shows changes of absorbance upon rotation of a polarizer switching from transparent to opaque. In addition, its suprastructure does not influence the luminescent properties of encapsulated chromophores, allowing the formation of colored anisotropic materials.

Ab initio calculation of electron–phonon coupling in monoclinic β-Ga2O3 crystal

The interaction between electrons and vibrational modes in monoclinic β-Ga2O3 is theoretically investigated using ab-initio calculations. The large primitive cell of β-Ga2O3 gives rise to 30 phonon modes all of which are taken into account in transport calculation. The electron-phonon interaction is calculated under density functional perturbation theory and then interpolated using Wannier–Fourier interpolation. The long-range interaction elements between electrons and polar optical phonon (POP) modes are calculated separately using the Born effective charge tensor. The direction dependence of the long-range POP coupling in a monoclinic crystal is explored and is included in the transport calculations. Scattering rate calculations are done using the Fermi golden rule followed by solving the Boltzmann transport equation using the Rode's method to estimate low field mobility. A room temperature mobility of 115 cm2/V s is observed. Comparison with recent experimentally reported mobility is done for a wide range of temperatures (30 K–650 K). It is also found that the POP interaction dominates the electron mobility under low electric field conditions. The relative contribution of the different POP modes is analyzed and the mode 21 meV POP is found to have the highest impact on low field electron mobility at room temperature.

Interpretation of Polar Orders Based on Electric Characterizations: Example of Pb(Yb $$_{1/2}$$ 1 / 2 Nb $$_{1/2}$$ 1 / 2 )O $$_3$$ 3 -PbTiO $$_3$$ 3 Solid Solution

Characterizing the polar order is a fundamental step in the understanding of a material and a necessity for application purposes since each polar order is associated with specific functionalities. Here, using the Pb(Yb\(_{1/2}\)Nb\(_{1/2}\))O\(_3\)-PbTiO\(_3\) (PYN-PT) solid solution as an example, we propose to differentiate the polar order based on two simple electrical characterization methods: measurement of the dielectric constant and hysteresis loops. Comparing the dielectric constant measured in high and low electric field conditions, we show that the polarization-electric field measurements may induce out-of-equilibrium phases. The better understanding of the effect of the measuring conditions on the polar order has led us to propose a new sequence of equilibrium polar orders in the PYN-PT solid solution at room temperature.

Self healing of open circuit faults: With active re-configurability and mimicry of synaptic plasticity

We discuss the self-repair of open faults in circuits using electrically conductive particles dispersed in an insulating fluid. The repair is triggered by the electric field developed across the open circuit in a current carrying interconnect and results in the formation of a bridge of particles across the gap. We illustrate and model the dynamics of the resistance of the self-healed route, Rb, in low field conditions. Furthermore, active control of Rb and active re-wiring are also demonstrated. Considering Rb to be akin to weights between nodes, the formation and re-wiring of routes and the control of Rb mimic synaptic plasticity in biological systems and open interesting possibilities for computing.

E/N effects on K0 values revealed by high precision measurements under low field conditions.

Ion mobility spectrometry (IMS) is used to detect chemical warfare agents, explosives, and narcotics. While IMS has a low rate of false positives, their occurrence causes the loss of time and money as the alarm is verified. Because numerous variables affect the reduced mobility (K0) of an ion, wide detection windows are required in order to ensure a low false negative response rate. Wide detection windows, however, reduce response selectivity, and interferents with similar K0 values may be mistaken for targeted compounds and trigger a false positive alarm. Detection windows could be narrowed if reference K0 values were accurately known for specific instrumental conditions. Unfortunately, there is a lack of confidence in the literature values due to discrepancies in the reported K0 values and their lack of reported error. This creates the need for the accurate control and measurement of each variable affecting ion mobility, as well as for a central accurate IMS database for reference and calibration. A new ion mobility spectrometer has been built that reduces the error of measurements affecting K0 by an order of magnitude less than ±0.2%. Precise measurements of ±0.002 cm(2) V(-1) s(-1) or better have been produced and, as a result, an unexpected relationship between K0 and the electric field to number density ratio (E/N) has been discovered in which the K0 values of ions decreased as a function of E/N along a second degree polynomial trend line towards an apparent asymptote at approximately 4 Td.

Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications.

Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

Performance Enhancement of Metal Floating Gate Memory by Using a Bandgap Engineered High-k Tunneling Barrier

With conventional nonvolatile flash memories approaching their scaling limit from cell-to-cell coupling and stress induced leakage current, many studies have been performed to explore the next generation memory technologies. Metal floating gate (FG) memory is one of the most promising candidates because of its less ballistic transport even with ultrathin floating gate (<10 nm). Enhancd memory performance including fast program speed, excellent data retention and program/erase (P/E) cycling endurance have been repored by P. Blomme et. al from IMEC. Moreover, S. Jayanti et. al explored that full Metal-FG could scaled down to even 1 nm thickness with excellent memory performance. Nevertheless, less attention had been paid on the study of tunneling layer which matches with full Metal-FG. Sufficient gate coupling ratio could obtained by using tunneling barrier without compromising the device performance. In our previous work , both the P/E speed and retention characteristic has been improved in the TaN floating gate flash memory based on the SiO2/HfO2 dual tunneling layer structure.The HfO2 layer adjacent to TaN was expected to suppress the inter-diffusion between tunneling dielectric and TaN FG. In this letter, bandgap engineered of the triple tunneling layer (SiO2/HfO2/Al2O3) has been demonstrated to be an effective method to optimize the performance of TaN Metal-FG. Compared to a device with a single SiO2 tunneling layer, faster program/erase speed and better data retention characteristics have been simultaneously achieved in this proposed structure. The schematic structure of a metal floating gate device is illustrated in Figure 1. P-type Si (100) wafers were cleaned by the standard Radio Corporation of America process. Devices with SiO2 (SiO2-4.5nm), SiO2/HfO2 (SiO2-2.7nm/HfO2-8nm) and SiO2/HfO2/Al2O3 (SiO2-2.7nm/HfO2-4nm/Al2O3-2nm) as tunneling layers are denoted as O-TaN , OH-TaN and OHA-TaN respectively. The thicknesses of tunneling layers were chosen for achieving the same effective oxide thickness (EOT). The memory characteristics such as operation speed and data retention were measured by using Agilent B1500A. The C-V hysteresis memory window of both O-TaN and OH-TaN device have been test. The improvement in the memory window for the OH-TaN device indicates the better carrier trapping capability of the stacked SiO2/HfO2 structure.It also can be attributed to the difference of the effective tunneling distance, which is resulted from the different potential drop when low-k and high-k dielectrics are employed as tunneling layer. Devices with SiO2/HfO2/Al2O3 (OHA) as tunneling layer was further characterized and compared with O-TaN and OH-TaN device. Compared to the O-TaN device, fast P/E speed along with large memory window is achieved with the OH-TaN and OHA-TaN device. Moreover, the device with OHA is slightly more advanced than the device with OH. The improvement of P/E speed in the OH-TaN and OHA-TaN structure can be explained by the energy band diagram under the program bias condition. Owing to the difference of voltage drop and bandgap between SiO2 and high-k (HfO2 and Al2O3), the effective tunneling distance is reduced in a high-k engineered tunneling layer structure. In addition, The reason that devices with OHA as tunneling layer shows slightly faster P/E speed than devices with OH as tunneling layer may attribute to a high defect state density at the interface of HfO2 and Al2O3. We also programmed the devices with an identical initial flat-band voltage to compare their room temperature retention characteristics. The OH-TaN and OHA-TaN structure exhibits negligible decrease in flatband voltage, whereas the control sample shows a significant loss of 2.7 V in flatband voltage in 104s. This can be attributed to the larger physical tunneling layer thicknesses of the engineered ones. The tunneling can be suppressed by large physical thickness under flat band or low electric field conditions. In this paper, a stacked high-k tunneling layer is proposed and investigated for TaN metal floating gate memory application. Compared to a single SiO2 tunneling layer, a stacked SiO2/HfO2 (SiO2-2.7nm/HfO2-8nm) and SiO2/HfO2/Al2O3 (SiO2-2.7nm/HfO2-4nm/Al2O3-2nm) tunneling layer structure have several memory performance improvements: a larger memory window, faster program/erase speed and better data retention characteristics. The improvement of P/E speed in the high-k tunneling barrier structure can be explained by the energy band diagram under the P/E bias condition. the effective tunneling distance is reduced Owing to the difference of voltage drop and bandgap between SiO2 and high-k (HfO2 and Al2O3). The performance enhancement of retention is attributed to the larger physical tunneling layer thicknesses of the high-k engineered ones. This work was supported by the National Natural Science Foundation of China (Grant No. 61306107, No. 61474137, No. 61404168, No. 61404160), China Postdoctoral Science Foundation funded project (No.2014M550866), and the Scientific Research Foundation of CUIT (KYTZ201318, J201404). Figure 1

Decline of cell viability and mitochondrial activity in mouse skeletal muscle cell in a hypomagnetic field.

Hypomagnetic field (HMF), one of the key environmental risk factors for astronauts traveling in outer space, has previously been shown to repress locomotion of mammalians. However, underlying mechanisms of how HMF affects the motor system remains poorly understood. In this study, we created an HMF (<3 μT) by eliminating geomagnetic field (GMF, ∼50 μT) and exposed primary mouse skeletal muscle cells to this low magnetic field condition for a period of three days. HMF-exposed cells showed a decline in cell viability relative to GMF control, even though cells appeared normal in terms of morphology and survival rate. After a 3-day HMF-exposure, glucose consumption of skeletal muscle cells was significantly lower than GMF control, accompanied by less adenosine triphosphate (ATP) and adenosine diphosphate (ADP) content and higher ADP/ATP ratio. In agreement with these findings, mitochondrial membrane potential of HMF-exposed cells was also lower, whereas levels of cellular Reactive Oxygen Species were higher. Moreover, viability and membrane potential of isolated mitochondria were reduced after 1 h HMF-exposure in vitro. Our results indicate that mitochondria can directly respond to HMF at functional level, and suggest that HMF-induced decline in cell functionality results from a reduction in energy production and mitochondrial activity.

Deviation from Kohler’s Rule Closely Correlated with the Field-Insensitive −logTDependence of Resistivity in SmTa2Al20

We have performed electronic transport measurements of single-crystal SmTa2Al20 to investigate its characteristic features of conduction electron scattering relevant to the field-insensitive −log T dependence of resistivity. The transverse magnetoresistance (MR) is always positive with H2 dependence over the investigated temperature range, indicating that MR due to the cyclotron motion of conduction electrons far exceeds the expected suppression of the Kondo scattering by a magnetic field. We found a strongly enhanced deviation from Kohler’s rule in MR in the low-field condition, which indicates that the conduction electron scattering by 4f electrons has a strong wave-vector dependence. We also found that the modified Kohler’s rule, which has been confirmed in some of the strongly correlated electron systems with quasi-two-dimensional crystal structures, holds in SmTa2Al20, providing the first example of a cubic three-dimensional system.

High Resolution Quantitative Lorentz Microscopy

The advent of aberration corrected transmission electron microscopy has led to considerable improvements in the field of high resolution electron microscopy imaging. In this paper we show how these developments are applied to imaging of magnetic structure in field free or low field conditions. Whilst the capability of increased spatial resolution is demonstrated on magnetic layers with a width of < 20nm we also consider how a pixelated detector can be used to dramatically increase the efficiency of the detection of the magnetic signal variation in the presence of strong diffraction contrast.