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Introduction In this work, we present the calibration of the NEWTON magnetic susceptometer for in-situ determination of the magnetic susceptibility of planetary surface rocks and regoliths. The susceptometer is based on inductive methods, and its operation does not require of sample preparation or manipulation. Current prototype has demonstrated capabilities for the determination of the complex magnetic susceptibility, i.e. real and imaginary component of the susceptibility [1, 2]. We propose the NEWTON susceptometer for the determination of the complex magnetic susceptibility, to provide valuable information about the regolith and surface rocks in rocky bodies of the solar system, to be used as a selection criterion of rocks for sample return missions or for the in-situ scientific studies of the magnetic properties during planetary missions. Calibration of the susceptometer Due to the design of the instrument and the nature of the available magnetic susceptibility patterns [3], there are not available susceptibility calibration samples traceable to primary patterns with characteristics compatible with this device. The calibration procedure comprises a comparative methodology, consisting in two steps: the manufacture of magnetic susceptibility patterns, to serve as calibration samples of the real and imaginary parts separately for the NEWTON susceptometer; and the comparison of the results from the prototype with those from reference equipment. The manufactured samples for the calibration of the real component of the magnetic susceptibility were made of ferrite powder diluted in a non-magnetic epoxy resin. Four samples of different mass content in ferrite powder were made, with the following distribution: a sample with 10% (weight %), a sample with 1%, a sample with 0,1% and a sample with 0,03% in ferrite powder. The homogeneity of the distribution of the ferrite powder within the samples was verified with X-ray images. The imaginary susceptibility calibration samples were constructed using different techniques and comparing the results with other reference equipment. The sample used for calibration is made of 2.5mm diameter steel spheres (rolling bearing balls) distributed in a cubic lattice in a resin matrix providing both isotropic real and imaginary magnetic susceptibility values. Environmental testing The most critical parts of the instrument have been submitted to qualification tests: vibration, thermal-vacuum and outgassing tests, applying the same requirements and test levels of those for the landing Mars mission, Exomars 2022, to demonstrate the capability of the instrument to withstand the interplanetary missions and space conditions. Application of the NEWTON susceptometer The characterization of the complex magnetic susceptibility of rocks is an unexplored tool to constrain the composition, structure and geological history of rocks in surface planetary exploration [4]. The instrument is designed to measure a dynamic range of the real susceptibility from χ’ = 10-4 S.I. to χ’ = 101 S.I. for the real susceptibility, representative values for the rocks of the Earth, Moon and Mars [5, 6, 7]. The imaginary susceptibility measurement procedure has a resolution in the order of χ” = 10-6. The sensor is suitable to be placed on board rovers, or to be used as a portable device during field campaigns and by astronauts in manned space missions. This sensor provides a great advantage compared to available commercial susceptometers, given that it does not require sample preparation, but only a minimum sample size (~50 x 20 x 20 mm). The current state of the susceptometer prototype consist of a portable device divided in two boxes: the Sensor Box (SB), containing the sensor core; and the Electronics Box (EV) containing the support electronics for the operation of the instrument (Figure 1). The application of susceptibility measurements during space missions have a potential impact in the surface regolith and rocks characterization. The analysis of the samples from the Apollo missions [4], the characteristics of the Martian magnetic field [5], works in stony meteorites [6], Earth impact areas [7] and Earth analogues [8] highlight the enhancement of the scientific research that in situ magnetic field and magnetic susceptibility measurements provide to the Lunar and Martian exploration. Figure 1. Image of the setup of the NEWTON instrument for in situ measurements during field campaigns, including reference samples for calibration. Acknowledgement This work has been funded by the Spanish Programme for Research, Development and Innovation under the grants of references ESP2017-88930-R and PID2020-119208RB-I00: MagAres and MINOTAUR, respectively, as well as the European Union Project NEWTON, of grant agreement 730041. References [1] J.L. Mesa et al. Feb. 2022. Submitted to IEEE Trans Instrum Meas. [2] M. Díaz Michelena et al. 2017, Sensor Actuat A-Phys, vol. 263, pp. 471-479 [3] https://www.nist.gov/mml/materials-science-and-engineering-division/magnetic-moment-and-susceptibility-standard-reference. NIST. Retrieved May 4, 2022. [4] M.S. Bentley et al. 2009, Planet Space Sci, vol. 57 (12), pp. 1491-1499. [5] P. Rochette et al. 2006, Astrobiology, vol 6(3), pp. 423-36. [6] P. Rochette 2010, Earth Planet. Sci. Lett., vol. 292, pp. 383–391. [7] A. Collareta 2016, Meteorit Planet Sci, vol. 51 (2), pp. 351–371 [8] J. Pati, etl al 2016, Curr Sci India, vol. 111 (3), pp. 535-542.

The main objective of this contribution is to present the evolution of NEWTON novel magnetic susceptometer for planetary exploration, a state of the art sensor for the measurement of the complex magnetic susceptibility developed in the frame of an EU H2020 funded project [1].The magnetic susceptibility is a complex parameter dependent on the external magnetic field amplitude, direction and frequency. NEWTON susceptometer has been developed to determine the magnetic susceptibility of rocks and soils, with the capability to determine not only the real part but also the imaginary part of the susceptibility.The calibration and validation process for the susceptometer prototype casted very good results in comparison with other commercial and high resolution laboratory devices, reaching a resolution in the order of χ = 10−4 (I.S. Vol. Susceptibility), representative of Earth, Moon and Mars rocks. The critical parts of the prototype have been subjected to different tests, i.e. vibration and TVT, to verify the capability to withstand the hard environmental conditions of interplanetary missions.In this work we discuss the potential contribution of NEWTON instrument on the technical and scientific objectives achievement in future investigations on the Moon, either as payload during in-situ exploration with rovers or in sample return missions, providing a useful tool for fast in place sample analysis.There are still open questions regarding Moon’s magnetic field and geological characteristics of the satellite. Most hypotheses to explain the magnetic characteristics and anomalies on the lunar surface invoke a thermally driven core dynamo during its Pre-Nectarian and Nectarian history [2]. However, this theory is problematical given the small size of the core and the required strong magnetic field strength of an ancient dynamo. Further investigations on the lunar samples from missions [3] indicate ancient magnetic fields with intensities of The use of scientific instruments like NEWTON susceptometer in rover exploration missions could shed some light on the ancient dynamo magnetic field, the magnetic and mineral composition of the lunar crust and other unanswered questions from the Moon.Acknowledgements:This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 730041 and the Spanish Programme of Research, Development and Innovation oriented to the challenges of the society under grant ESP2017-88930-R. References:[1] M.Diaz Michelena, J.L Mesa Uña, M. Perez Jimenez, M. Maicas Ramos, P. Cobos Arribas, C. Aroca Hernandez-Ros, Sensors and Actuators, A: Physical, volume 263, pages 471-479 (2017)[2] Tikoo, S.M., Weiss, B.P., Cassata, W.S., Shuser, D.L., Gattacceca, J., Lima, E.A., Suavet, C., Nimmo, F. & Fuller, M.D. Earth Planet. Sci. Lett., 404: 89-97 (2014)[3] Tsunakawa, H., Takahashi, F., Shimizu, H., Shibuya, H., & Matsushima, M. Icarus 228: 35-53 (2014).[3] Fuller, M. (1974). Reviews of Geophysics, 12 – 1, 101-103 (1974)

In this work, we developed a novel approach for the preparation of molecularly imprinted polymer (MIP) coatings directly onto magnetic multicore nanoparticles (MMCs) using alternating magnetic fields to trigger the polymerization reaction. MIPs were synthesized with rhodamine 123 (R123) as model template molecule, methacrylic acid as functional monomer, and trimethylolpropane trimethacrylate as cross-linker. The amount of iron oxide nano particles and the composition of the polymerization mixture were optimized to enable the thermal polymerization of a thin MIP shell on each MMC using electromagnetic heating without altering the properties of the recognition layer. The thickness of the polymerized MIP layer grafted onto the MMCs was fine-tuned by adjusting the dose of electromagnetic field (101.4 kHz, total power dissipation = 105 W). The resulting magnetic multicore MIP nanoparticles (MMC-MIPs) were characterized by FT-R and X-ray diffraction spectroscopy, transmission electron microscopy, and dynamic light scattering.

A device named magnetic susceptometer for a complete determination of the magnetic complex susceptibility of materials and minerals has been conceived and manufactured as a complement for the in situ characterization of rocks during high resolution magnetic prospections. In this work a device and its capabilities for susceptibility measurements are described, the calibration performed with artificial samples, and the values of real and imaginary susceptibility of natural samples in a range comprising: χ = 10−4 to 10−7 [SI], representative of Earth and also Mars rocks.

NEWTON novel instrument for magnetic susceptibility on site characterisation

In this paper we describe the development of devices devoted to the characterization of the magnetic complex susceptibility of materials and minerals. The work is focused on the evolution, calibration and validation of the prototypes foreseen in H2020 NEWTON project, a magnetic susceptometer for the in-situ characterization of rocks during high resolution magnetic prospections, with characteristics compatible with space vehicles and hand-held instrumentation. The instrument consists of a novel susceptometer design based on an inductive method and a COTS magnetometer for the vector magnetic field characterization. The calibration and validation process for Prototype 1 casted very good results in comparison with other commercial and high resolution laboratory devices, reaching a resolution in the order of χ = 10 - 4 (I.S. Vol. Susceptibility), representative of Earth, Moon and Mars rocks. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 730041. Peerreview

Anisotropic magnetoresistive (AMR) magnetic sensors are often chosen as the magnetic transducer for magnetic field sensing in applications with low to moderate magnetic field resolution because of the relative low mass of the sensor and their ease of use. They measure magnetic fields in the order of the Earth magnetic field (with typical sensitivities of 1‰/G or 10−2‰/μT), have typical minimum detectable fields in order of nT and even 0.1 nT but they are seriously limited by the thermal drifts due to the variation of the resistivity with temperature (∼2.5‰/°C) and the variation of the magnetoresistive effect with temperature (which affects both the sensitivity of the sensors: ∼2.7‰/°C, and the offset: ±0.5‰/°C). Therefore, for lower magnetic fields, fluxgate vector sensors are generally preferred. In the present work these limitations of AMR sensors are outlined and studied. Three methods based on lock-in amplifiers are proposed as low noise techniques. Their performance has been simulated, experimentally tested and comparatively discussed. The developed model has been also used to derive a technique for temperature compensation of AMR response. The final goal to implement these techniques in a space qualified applied specific integrated circuit (ASIC) for Mars in situ exploration with compact miniaturized magnetometers. Peerreview

INSPEC Accession Number: 15298193 We have designed and fabricated a microelectromechanical device, based on the alternating field gradient concept, to measure surface magnetic field gradient on planets. Its sensitivity is 4 10 -4 T/m, which is appropriate for magnetite outcrops and areas with rocks formed at different stages recording geomagnetic field reversals. We present the results obtained with three different prototypes. The work of J. L. Mesa was supported by INTA training Grant TS09/12. This work has been done in the frame of PRI-PIBUS-2011-1150 and 1182 grants of the subprogram of international and bilateral projects of the Spanish Ministry of Science and Innovation. The work at CMU is supported by the National Science Foundation through Materials World Network under Grant DMR1106943. Peerreview

The magnetic properties of CoP electrodeposited alloys can be easily controlled by layering the alloys and modulating the P content of the different layers by using pulse plating in the electrodeposition process. However, because of its amorphous nature, the study of the interface quality, which is a limitation for the optimization of the soft magnetic properties of these alloys, becomes a complex task. In this work, we use Rutherford backscattering spectroscopy (RBS) to determine that electrodeposited Co0.74P0.26/Co0.83P0.17 amorphous multilayers with layers down to 20 nm-thick are composed by well-defined layers with interfacial roughness below 3 nm. We have also determined, using magnetostriction measurements, that 4 nm is the lower limitation for the layer thickness. Below this thickness, the layers are mixed and the magnetic behavior of the multilayered films is similar to that shown by single layers, thus going from in-plane to out-of-plane magnetic anisotropy. Therefore, these results establish the range in which the magnetic properties of these alloys can be controlled by layering.

Tb x Fe 1− x thin films deposited by sputtering on Mo were investigated structurally and magnetically. The microstructure consists of TbFe 2 nanoparticles embedded in an amorphous matrix, and the Tb content can be correlated with an increase in the volume of these nanoparticles. Similar microstructure and behavior were found when TbFe 2 was deposited on glass and on a Pt buffer layer. Nevertheless, thermal treatments promote a different effect, depending on the mechanical stiffness of the buffer layer. The layers deposited on Mo, a rigid material, show crystalline TbFe 2 together with α-Tb phase upon thermal treatment. In contrast, TbFe 2 does not crystallize properly on Pt, a material with a lower stiffness than Mo. Intermediate results were observed on the film deposited on glass. Experimental results show the impact of the buffer stiffness on the crystallization process. Moreover, the formation of α-Tb appears to be fundamental to crystallized TbFe 2 on layers deposited on rigid buffers.

We report on the size, structure and magnetic properties of Ni nanoparticles fabricated with a free-jet sputtering nanoparticle source. It is found how the pressure of the inert gas and the diameter of the source nozzle can control the particle size and coercivity in a wide range. Measurements of the specific magnetic moment of Ni nanoparticles are reported. A particular growing regime is found at high pressures over 1.8 mbar observing a further aggregation process that leads to nanoparticle agglomerates with diameters larger than 100 nm with a low dispersion in size.

In this paper we present an analytical model for describing the sensitivity of a toroidal fluxgate sensor. The model is based on a simplified schematics for the hysteresis loop of the fluxgate core that only includes the coercivity, the saturation field and the saturation magnetization. In spite of this simplicity, the model has been successfully used to describe the variation of the sensitivity of a PCB-based fluxgate sensor with the amplitude and the frequency of the driving current. The model has been developed for a toroidal configuration but can be easily modified to describe other geometries.

Py/Gd/Py trilayers (Py: :Fe 20 Ni 80 ) have been electrical and magnetically characterized as a function of the temperature. Results show a weak Py-Gd exchange coupling probably due to the Ni interdiffusion into the Gd layer. These results have been compared with magnetic measurements in Py/Gd double bilayers ([Py/Gd/Mo] 2 ). An enhancement of the Py-Gd exchange coupling has been obtained in these samples where the Ni concentration in the Gd layer is almost null.

We have studied the influence of the growth conditions on the structural characteristics of sputtered Py(Fe20Ni80)/ Gd/Py(Fe20Ni80) thin films. Auger electron spectroscopy reveals the existence of Ni in the Gd layer. The Ni concentration profile appears asymmetric with a higher concentration close to the top Py layer. This asymmetrical Ni concentration produces a different coercivity of each Py layer. It is possible to reduce the Ni interdiffusion by using multilayers based on Py/Gd bilayers separated by Mo spacers between the Py/Gd bilayers. In these samples we have obtained an enhancement of the structural and magnetic properties.

The influence of magnetic anisotropy on magnetoresistance has been studied in magnetic-non-magnetic-magnetic sandwiches. A numerical model has been developed considering different anisotropies in each magnetic layer and different exchange couplings between them. Both contributions to the magnetoresistance are evaluated; anisotropic and giant magnetoresistance (GMR). Appropriate magnetic anisotropy configurations allow GMR without antiferromagnetic coupling between the magnetic layers. Sandwiches of permalloy-copper-permalloy have been obtained in a dc magnetron sputtering system with different thickness and different anisotropy distributions in order to make a comparison between the experimental magnetoresistance and the numerical results.

Several samples of NdFeB and SmCo permanent magnets have been irradiated with gamma rays up to different total irradiation doses until 1Mrad(Si). Magnetic properties of the samples have been measured at different temperatures before and after irradiation. The modifications of the magnetic parameters are presented. From these results it is highlighted which permanent magnets show more resistance to radiation and are more suitable to be included in devices for space applications or high radiation environments.

A new planar fluxgate is presented. The primary coil consists on a spiral grown on a ferrite disc in order to increase the magnetic field produced by the driving current and also to compensate for superimposed external magnetic fields. Two metallic spirals in opposite phase have been mounted over this coil as the secondary winding. They detect the signal induced by two stripes of ferromagnetic amorphous metal. The fluxgate shows a wide dynamic range and a good linear behaviour up to 50 kHz, with a maximum sensitivity of 12.7 V/T.

A device to obtain an estimate of the spectrum of a time‐variable magnetic field has been developed. The amplitude of each spectral component of the magnetic field series is obtained by analyzing with a double demodulation technique the signal generated from a flux‐gate‐like detector operating in open loop configuration. This device shows a sensitivity of about 1 mV/nT in the range from 0 to 300 Hz. For frequencies higher than 300 Hz the sensitivity decreases, and a correction factor that depends on the transfer function of the electronic device must be applied. The present device can be applied to environmental measurements, industrial applications, traffic control, and scientific research.

We report the design, fabrication, and characterization of a new system that combines the performances of two different types of magnetic characterization systems, Alternating Gradient Force Magnetometers (AGFM) and susceptometers. The flexibility of our system is demonstrated by its capability to be used as any of them, AGFM or susceptometer, without any modification in the experimental set-up because of the electronics we have developed. Our system has a limit of sensitivity lower than 5 × 10(-7) emu. Moreover, its main advantage is demonstrated by the possibility of measuring small quantities of materials under DC or AC magnetic fields that cannot properly be measured with a commercial vibrating sample magnetometers or AGFM.

In this work, we experimentally justify that the control of the mechanical stress induced during the deposition of sputtered amorphous magnetostrictive (Fe80Co20)80B20 allows a custom design of its magnetic properties. FeCoB multilayers have been sputtered on thermal oxide Si substrates with different buffer materials. The crystalline quality and the thermomechanical properties of the buffer layer influence both the coercive and the anisotropy field. Those buffer layers with both high rigidity and poor thermal conductivity do not allow the dissipation of energy of the incoming sputtered material. Therefore, the mechanical stresses related to the deposition process cannot be released, leading to magnetic layers with high easy-axis coercive field and low anisotropy field. This shows that the mechanical stresses accumulated during deposition are a key parameter for the control of coercivity.

The main goal of this work is to generate a method to control the magnetic properties of magnetostrictive metals (anisotropy and coercive field) without affecting the total magnetostriction. Multilayers of amorphous (Fe80Co20)80B20 are sputtered changing alternatively the anisotropy direction of the successive layers. The hysteresis loops show how the anisotropy field can be controlled by playing with the thickness ratio of the layers. Additionally, a clear decrease of the coercive field when the anisotropy direction rotates 90° from layer to layer is observed. This effect seems to have its origin in the mechanical energy accumulated in each layer.

In this work we report on the magnetic and electrical properties of Permalloy∕gadolinium∕Permalloy (Py∕Gd∕Py) trilayers at low temperatures. These results are complemented with a structural study and numerical calculations. The Py-Gd coupling field is derived from magnetoresistance measurements in the transverse configuration of the trilayer with a Permalloy thickness lower than its exchange correlation length. The coupling field obtained was low, likely due to the presence of low Curie temperature Gd1−xNix alloys at the Py∕Gd interfaces.

A new closed flux stripe domain model is proposed to gain more insight into the magnetic behavior of films with weak perpendicular magnetic anisotropy (PMA). Its main novelty is a new flux-closure pattern in which magnetic flux follows semicircular paths. This approximation has been inspired by the magnetization distribution obtained by some researchers by micromagnetic numerical simulation for this kind of film. This model arises as a good alternative to models based on the Landau-Lifshitz closure pattern and fits rather well the recently observed enlargement of the surface coercivity of strips with weak PMA under the in-plane demagnetizing field effect.

The effect of reduced lateral dimension on the magnetic behavior of long microstrips with weak perpendicular magnetic anisotropy has been studied. The hysteresis loops of the surface and the whole volume of microstrips and large films have been recorded by magneto-optic Kerr effect magnetometry and vibrating sample magnetometry. Also, the magnetic structure of the microstrips and its evolution under an applied field have been studied by magnetic force microscopy and the Bitter technique. It has been observed that the transversal dimension of the microstrips gives rise mainly to an in-plane demagnetizing field which affects their hysteresis loops and magnetic structure in a different manner. A great increase in the surface coercivity in the transversal direction of the microstrips is the main unexpected effect that has been observed. On the other hand, the magnetic structure in remanence and its evolution with increasing thickness have not revealed a significant dependence on the direction of the last satu...

CoP electrolytic monolayers and multilayers were grown over copper wires using a constant or pulsed electrical current density, exhibiting radial or planar anisotropy, respectively. Over the surface of a monolayer, multilayers of different thicknesses were deposited. The surface radial anisotropy evolves to a planar one as the overlayer thicknesses increase. The surface magnetization is coupled with the bulk anisotropy for overlayer thickness up to ≈ 2 μm.

Thin films and arrays of lines of magnetic CoNiFe alloy have been produced by electrodeposition. A magnetic field was applied during the electrodeposition process in order to induce a magnetic anisotropy in the sample. The dependence of the magnetic properties and the magnetic domain structures on the thickness of the films is reported. In addition to this, the magnetic properties and the domain structure of a thin film and an array of lines, with the same thickness and deposited in the same conditions, have been compared. An increase in the coercivity of the array of lines has been shown.