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. 2022 Apr 8;8(14):eabj2487. doi: 10.1126/sciadv.abj2487

Ferromagnetism and exchange bias in compressed ilmenite-hematite solid solution as a source of planetary magnetic anomalies

Satoshi Ohara 1,*, Takashi Naka 2, Takeshi Hashishin 3
PMCID: PMC8993106  PMID: 35394841

Abstract

We propose a compressed ilmenite-hematite solid solution as a new potential source of Earth’s magnetic anomalies. The 0.5FeTiO3·0.5Fe2O3 solid solution compressed by collision synthesis with super-high-energy ball milling showed a decrease in molar volume of approximately 1.8%. Consequently, the sample showed a saturation magnetization of 1.5 ampere square meter per kilogram (Am2/kg) at 300 kelvin, a Curie temperature of 990 kelvin, and a magnetic exchange bias below 100 kelvin, e.g., 1.7 × 105 ampere per meter at 60 kelvin. Ilmenite-hematite solid solutions are common mineral systems in most mafic igneous and metamorphic rocks, and the compressive force in the rocks is generated by the high pressure in the upper mantle or by shock events with high pressure such as the collision of these rocks with meteorites. Therefore, we consider that the compressed ilmenite-hematite solid solution is an additional candidate source of other planetary magnetic anomalies including those in the Moon and Earth.

The compressed ilmenite-hematite solid solution is a potential candidate source of planetary magnetic anomalies.

INTRODUCTION

Earth’s magnetic anomalies are commonly attributed to the presence of magnetite, hematite, titanomagnetite, and pyrrhotite minerals. Magnetite (Fe3O4) shows strong ferromagnetism, and hematite (α-Fe2O3) shows antiferromagnetism with superimposed weak ferromagnetism (1). Ilmenite (FeTiO3) is a common mineral in nature and usually shows solid solutions toward α-Fe2O3; therefore, ilmenite-hematite (IH) solid solutions exist in most mafic igneous and metamorphic rocks. The intermediate members of the IH mineral series have strong ferrimagnetism (2), which is preserved only in rapidly cooled volcanic rocks. In addition, the IH natural mineral intergrowth series usually has large and stable magnetism, the so-called lamellar magnetism (3), formed through a natural process of phase separation during slow cooling over millions of years. Despite extensive advances in the study of this series including the recent investigations of lamellar magnetism (4–7), understanding the full nature of magnetism in the minerals and intergrowths in the IH solid solution series remains a great challenge. In this study, we provide experimental evidence of a new type of ferromagnetism with high Curie temperature and a large magnetic exchange bias in the compressed IH solid solution. These magnetic properties are of crucial importance in the study of planetary magnetic anomalies.

RESULTS

Ferromagnetism in compressed IH solid solution

The compressed IH solid solution was prepared by super-high-energy ball milling (8–11). The 0.5FeTiO3·0.5Fe2O3 solid solution sample shows a decrease in molar volume of approximately 1.8%, which corresponds to that of a single crystal of FeTiO3 under a high pressure of 5 GPa at 300 K. Consequently, the oxidation state in FeTiO3 changes to almost Fe3+Ti3+ from Fe2+Ti4+, resulting in the emergence of ferromagnetism (fig. S1 and table S1). The details were described in our previous report (11).

Figure 1A shows the magnetization M as a function of the applied magnetic field H at 300 K. The sample showed a mixed magnetic behavior between ferromagnetism and paramagnetism. The saturation magnetization Ms estimated from the straight line extrapolated to H of 0 A/m was approximately 1.5 Am2/kg. This value is three times higher than that for antiferromagnetic hematite with weak ferromagnetism, e.g., 0.5 Am2/kg (1) but lower than those of strongly ferromagnetic magnetite (1) and ferrimagnetic IH solid solution series (2). The saturation remanent magnetization Mr and coercivity Hc of the sample at 300 K were 0.3 Am2/kg and 24 × 103 A/m, respectively (Fig. 1B). We measured the magnetization of the sample at 100 and 5 K (fig. S2), and the Ms, Mr, and Hc values are plotted in Fig. 1C. The slope of Ms versus temperature for the sample is gentler than those for the synthetic IH solid solutions without lattice compression (12–15). Therefore, we consider that the ferromagnetism in the compressed IH solid solution sample is not related to conventional ferrimagnetism in the IH solid solution series.

Fig. 1. Magnetic properties of compressed 0.5FeTiO3·0.5Fe2O3 sample.

Fig. 1.

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(A) Magnetization measured at 300 K. (B) Hysteresis data for field strengths up to 3.5 × 105 A/m. (C) Temperature dependence of saturation magnetization Ms, remanent magnetization Mr, and coercivity Hc. Ms/Mr values are 2.63, 3.15, and 4.70 at 5, 100, and 300 K, respectively.

High Curie temperature

Figure 2 shows the temperature dependence of magnetization at 4 × 105 A/m from room temperature to 1073 K. We found that the Curie temperature Tc of the compressed IH solid solution sample is 990 K. This value is much higher than that (500 K) for the synthetic 0.5FeTiO3·0.5Fe2O3 solid solution without lattice compression (12, 13), hence increasing the depth range in Earth’s mantle across which this new type of magnetism would apply. Therefore, we propose that the ferromagnetism in the compressed IH solid solution is a new type of magnetism, and it is different from conventional ferrimagnetism. Notably, the Tc of the sample is higher than 843 to 853 K for strongly ferromagnetic magnetite and 943 K for weakly magnetic hematite (1). It is also higher than the unblocking temperature of 923 to 940 K for the lamellar magnetism in IH natural mineral intergrowth (16, 17).

Fig. 2. Magnetic properties of compressed 0.5FeTiO3·0.5Fe2O3 sample at high temperature.

Fig. 2.

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The magnetization was measured under a magnetic field of 4 × 105 A/m in vacuum. The Curie temperature Tc is approximately 990 K.

Large magnetic exchange bias

We consider that the ilmenite component acts as the ferromagnetic phase and the hematite component acts as the antiferromagnetic phase in the compressed 0.5FeTiO3·0.5Fe2O3 sample. The interface between the ferromagnetic and antiferromagnetic phases is to be expected for the generation of magnetic exchange bias, which is a phenomenon whereby the hysteresis loop of a soft magnetic phase is shifted by an amount HE along the applied field axis owing to its interaction with a hard magnetic phase. Figure 3 shows the hysteresis loops measured at 5 K after zero-field cooling with different room temperature pretreatments. Before zero-field cooling, the examined samples were pretreated at 300 K by applying a magnetic field H of +44 or −44 × 105 A/m to establish positive or negative remanent, respectively. It is found that the two hysteresis loops are shifted by the positive (Fig. 3A) and negative (Fig. 3B) remanent treatments. This is the second observation of evident exchange bias in synthetic IH solid solution samples (18), although it has been observed in the lamellar magnetism in natural IH minerals (5–7, 19–23). Figure 3C shows the difference between the upper and lower hysteresis branches (Fig. 3, A and B).

Fig. 3. Hysteresis loops measured at 5 K after zero-field cooling with different pretreatments.

Fig. 3.

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(A) Pretreatment with positive room temperature remanence. (B) Pretreatment with negative room temperature remanence. (C) The lower hysteresis branch is subtracted from the upper branch in the case of negative exchange bias. The estimated shift of the loop center (dashed line) indicates an exchange bias. (D) Temperature dependence of exchange bias HE. ZFC, zero-field cooling.

We measured the hysteresis loops from 5 to 160 K (fig. S3) to quantify HE (fig. S4), and their values are plotted in Fig. 3D. The estimated shift of the loop center indicated an exchange bias (HE) of approximately 1.7 × 105 A/m at 60 K. This large value is comparable to that for the lamellar magnetism at 45 K in natural mineral intergrowth with the most-fine nanometer-scale lamellae (23), and it is orders of magnitude larger than those in any other natural mineral intergrowths (5, 19–22). In addition, it is found that the compressed IH solid solution showed HE below 100 K, which is higher than the temperatures for the lamellar magnetism in natural mineral intergrowths (5, 23). In these cases, HE was observed below a Néel temperature of ilmenite lamellae, e.g., TN of 57 K, because HE is due to the interface between the ferrimagnetism in the contact layers of the titanohematite and the antiferromagnetism in the ilmenite lamellae (23). On the other hand, we consider that the two phases responsible for HE in the compressed IH solid solution are the ferromagnetism in the ilmenite component acting as the soft magnetic phase and the antiferromagnetism in the hematite component acting as the hard magnetic phase, i.e., coupling between the compressed ilmenite and hematite components.

Then, we suppose that these two phases in the compressed IH sample contribute to the generation of self-reversed thermoremanent magnetization (SR-TRM), which was found in volcanic rocks from Haruna (24, 25) and attributed to intermediate members of the IH solid solution series (12). Although the mechanism of SR-TRM in IH minerals remains poorly understood, it is considered to require the presence of two phases, namely, a strongly magnetic stable phase and a weakly magnetic metastable phase (26). We consider that the compressed IH solid solution may be potentially useful for the generation of SR-TRM induced by the coupling between the ferromagnetic phase of the ilmenite component and the antiferromagnetic phase with the superimposed weak ferromagnetism of the hematite component.

DISCUSSION

To confirm a new type of ferromagnetism with high Tc in the compressed IH solid solution, we released the lattice compression in the sample by heat treatment at 1273 K in vacuum. We found that the peak position for the sample after heat treatment was clearly shifted to a d-spacing higher than that for the compressed sample (fig. S5). This shift in peak position suggests that the lattice compression in the IH solid solution can be released by heat treatment. Although the heat-treated sample showed a hysteresis loop (Fig. 4A), its Tc changed to 615 K (Fig. 4B). This temperature is much lower than 990 K for the compressed sample, and it is consistent with the conventional ferrimagnetism in the IH solid solutions without lattice compression (12, 13). Moreover, the heat-treated sample showed no shift of the hysteresis loop at different room temperature pretreatments, i.e., no HE (fig. S6). Therefore, we conclude that the ferromagnetism with high Tc in the compressed IH sample is a previously unknown magnetism, and it clearly differs from the conventional ferrimagnetism in IH solid solutions series.

Fig. 4. Magnetic properties of heat-treated 0.5FeTiO3·0.5Fe2O3 sample.

Fig. 4.

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(A) Hysteresis data measured at 300 K. (B) Magnetization was measured under a magnetic field of 4 × 105 A/m in the temperature range from 300 to 1073 K in vacuum.

Overall, our results suggest that the compressed IH solid solution is responsible for the source of Earth’s magnetic anomalies. Members of the IH solid solution series are common minerals in nature, existing as an accessory phase in most mafic igneous and metamorphic rocks. For example, they are derived from the upper mantle down to depths of approximately 400 km, and thus, with pressures of 12 to 13 GPa (27), their compressed state is obtained. The hydrostatic and isotropic pressure is formed in the mantle, leading to thermodynamic equilibrium. In the contrary, the nonhydrostatic pressure occurs between the balls uniaxially in the ball milling system. However, we consider that the thermodynamic state is obtained partially in the compressed IH solid solution prepared by super-high-energy ball milling, because some thermodynamic effects of nonhydrostatic pressure on the magnetic properties in magnetite are derived (28). Then, the compression rate of the sample is approximately 1.8%, which corresponds to that of a single crystal of trigonal FeTiO3 under a high pressure of approximately 5 GPa at 300 K generated using a diamond anvil cell (29). It is reported that a pressure of 5 GPa occurs at a depth of 160 km, where the temperature is approximately 1073 K (30). Although this value is slightly higher than the Tc of the compressed sample at an ordinary pressure, it is reported that the Tc of magnetite increases with pressure (31, 32). Therefore, we predict that the compressed sample shows the ferromagnetism at 5 GPa and 1073 K. On the basis of these findings, we suggest that some compressed IH mineral series at depths in the upper mantle contribute to in situ Earth’s magnetic anomalies.

The magnetic anomalies are also observed on the Moon and Mars. It is known that both celestial bodies experienced shock events with high pressure upon collision with meteorites, such that intense compressive forces were added to those collision sites. We consider that the uniaxial pressure by collision with meteorites is similar to that by collision synthesis with super-high-energy ball milling. It is reported that geikielite-rich ilmenite rocks are important for the Moon’s anomalies (33). It is considered that the anomalies in Mars require very large rock volumes over areas of hundreds of square kilometers and extending to depths of 20 to 30 km (34, 35), where ilmenite exists as an accessory mineral. By taking together these findings and our results, we predict that the rocks containing the compressed ilmenite series are potential candidate sources of other planetary magnetic anomalies including those in the Moon and Earth.

Last, we discuss the relationships between the ferromagnetism in the compressed IH solid solution and the lamellar magnetism in the natural mineral intergrowth (3–5). It is considered that the lamellar magnetism is responsible for the unusually large and stable remanent magnetization in rocks. For example, it is observed in grains of titanohematite (FeTiO3 bearing Fe2O3) that crystallized and phase-separated (exsolved) nearly 1 billion years ago (23). This mineral contains abundant nanoscale exsolution lamellae of ilmenite, and ferrimagnetism occurs at the interface between the paramagnetic ilmenite lamellae and the antiferromagnetic titanohematite host. At present, we assume that the compressive force is generated in the contact layers of the ilmenite lamellae by the heterogeneous interface between the ilmenite lamellae and the titanohematite host, i.e., their lattice mismatch. We believe that the ferromagnetism reported in this study could occur in the compressed contact layers of the ilmenite lamellae and that the charge ordering in contact layers of lamellar magnetism may be influenced by the charge transfer from Fe2+ to Fe3+ in FeTiO3 with high pressure.

MATERIALS AND METHODS

Hysteresis loop measurements

We measured the magnetic properties using a conventional superconducting quantum interference device magnetometer (MPMS-XL, Quantum Design) under a magnetic field of up to 40 × 105 A/m in the temperature range from 5 to 300 K for dc magnetization.

Curie temperature measurements

We measured the magnetization using a conventional vibrating sample magnetometer (BHV-50H, Riken Denshi Co. Ltd.) under a magnetic field of 4 × 105 A/m in the temperature range from 300 to 1073 K in vacuum. Sample powder installed into a copper capsule was settled in a glass vacuum chamber. The Curie temperature Tc of the sample was determined by an empirical form with two exponents to reproduce the curve for the temperature dependence of magnetization below Tc.

X-ray diffraction measurements

Powder x-ray diffraction patterns were measured for the samples with Ni-filtered Cu Kα radiation (λ = 1.4506 Å).

Acknowledgments

Funding: This work was supported by Grant-in-Aid for the Cooperative Research Project of Design & Engineering by Joint Inverse Innovation for Materials Architecture of the Ministry of Education, Culture, Sports, Science, and Technology of Japan (to S.O.).

Author contributions: Characterization: S.O. Magnetic measurements: T.N. X-ray diffraction measurements: T.H. Supervision: S.O. Writing—original draft: S.O. Writing—review and editing: S.O., T.N., and T.H.

Competing interests: The authors declare that they have no competing interests.

Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.

Supplementary Materials

This PDF file includes:

Figs. S1 to S6

Table S1

Click here for additional data file. (1.6MB, pdf)

REFERENCES AND NOTES

  • 1.Dunlop D. J., Kletetschka G., Multidomain hematite: A source of planetary magnetic anomalies? Geophys. Res. Lett. 28, 3345–3348 (2001). [Google Scholar]
  • 2.Ishikawa Y., Akimoto S., Magnetic property and crystal chemistry of ilmenite (MeTiO3) and hematite (αFe2O3) system II. Magnetic property. J. Phys. Soc. Jpn. 13, 1298–1310 (1958). [Google Scholar]
  • 3.Robinson P., Harrison R. J., McEnroe S. A., Hargraves R. B., Lamellar magnetism in the haematite–ilmenite series as an explanation for strong remanent magnetization. Nature 418, 517–520 (2002). [DOI] [PubMed] [Google Scholar]
  • 4.Robinson P., Harrison R. J., McEnroe S. A., Hargraves R. B., Nature and origin of lamellar magnetism in the hematite–ilmenite series. Am. Mineral. 89, 725–747 (2004). [DOI] [PubMed] [Google Scholar]
  • 5.McEnroe S. A., Robinson P., Langenhorst F., Frandsen C., Terry M. P., Ballaran T. B., Magnetization of exsolution intergrowth of hematite and ilmenite: Mineral chemistry, phase relations, and magnetic properties of hemo-ilmenite ores with micron- to nanometer-scale lamellae from Allard Lake, Quebec. J. Geophys. Res. 112, B10103 (2007). [Google Scholar]
  • 6.McEnroe S. A., Robinson P., Miyajima N., Fabian K., Dyar D., Sklute E., Lamellar magnetism and exchange bias in billion-year-old titanohematite with nanoscale ilmenite exsolution lamellae: I. Mineral and magnetic characterization. Geophys. J. Int. 206, 470–486 (2016). [Google Scholar]
  • 7.Robinson P., McEnroe S. A., Jackson M., Lamellar magnetism and exchange bias in billion-year-old metamorphic titanohematite with nanoscale ilmenite exsolution lamellae - II: Exchange-bias at 5 K after field-free cooling of NRM and after cooling in a +5 T field. Geophys. J. Int. 208, 895–917 (2017). [Google Scholar]
  • 8.Ohara S., Tan Z., Noma J., Hanaichi T., Sato K., Abe H., Collision synthesis of unique carbon nanomaterials inspired by the Allende meteorite. Solid State Commun. 150, 198–200 (2010). [Google Scholar]
  • 9.Tan Z., Chihara H., Koike C., Abe H., Kaneko K., Sato K., Ohara S., Interstellar analogs from defective carbon nanostructures account for interstellar extinction. Astronomical J. 140, 1456–1461 (2010). [Google Scholar]
  • 10.Hashishin T., Tan Z., Yamamoto K., Nan Q., Kim J., Numako C., Naka T., Valmalette J.-C., Ohara S., Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling. Sci. Rep. 4, 4700 (2014). [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11.Ohara S., Naka T., Sunakawa K., Kubuki S., Senna M., Hashishin T., Emergence of ferromagnetism due to charge transfer in compressed ilmenite powder using super-high-energy ball milling. Sci. Rep. 10, 5293 (2020). [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Ishikawa Y., Akimoto S., Magnetic properties of the FeTiO3-Fe2O3 solid solution series. J. Physical Soc. Japan 12, 1083–1098 (1957). [Google Scholar]
  • 13.Brown N. E., Navrotsky A., Nord G. L., Banerjee S. K., Hematite–ilmenite (Fe2O3–FeTiO3) solid solutions: Determinations of Fe–Ti order from magnetic properties. Am. Mineral. 78, 941–951 (1993). [Google Scholar]
  • 14.Takada Y., Nakanishi M., Fujii T., Takada J., Preparation and characterization of (001)- and (110)-oriented 0.6FeTiO3·0.4Fe2O3 films for room temperature magnetic semiconductors. Appl. Phys.Lett. 92, 252102 (2008). [Google Scholar]
  • 15.Bocher L., Popova E., Nolan M., Gloter A., Chikoidze E., March K., Warot-Fonrose B., Berini B., Stéphan O., Keller N., Dumont Y., Direct evidence of Fe2+–Fe3+ charge ordering in the ferrimagnetic hematite–ilmenite Fe1.35Ti0.65O3-δ thin films. Phys. Rev. Lett. 111, 167202 (2013). [DOI] [PubMed] [Google Scholar]
  • 16.McEnroe S. A., Brown L. L., Palaeomagnetism, rock magnetism and geochemistry of Jurassic dykes and correlative redbeds, Massachusetts, USA. Geophys. J. Int. 143, 22–38 (2000). [Google Scholar]
  • 17.McEnroe S. A., Brown L. L., A closer look at remanence-dominated aeromagnetic anomalies: Rock magnetic properties and magnetic mineralogy of the Russell Belt microcline-sillimanite gneiss, northwest Adirondack Mountains, New York. J. Geophys. Res. 105, 16437–16456 (2000). [Google Scholar]
  • 18.Fabian K., Miyajima N., Robinson P., McEnroe S. A., Ballaran T. B., Burton B. P., Chemical and magnetic properties of rapidly cooled metastable ferri-ilmenite solid solutions: Implications for magnetic self-reversal and exchange bias—I. Fe-Ti order transition in quenched synthetic ilmenite 61. Geophys. J. Int. 186, 997–1014 (2011). [Google Scholar]
  • 19.McEnroe S. A., Harrison R. J., Robinson P., Golla U., Jercinovic M. J., Effect of fine-scale microstructures in titanohematite on the acquisition and stability of natural remanent magnetization in granulite facies metamorphic rocks, southwest Sweden: Implications for crustal magnetism. J. Geophys. Res. 106, 30523–30546 (2001). [Google Scholar]
  • 20.McEnroe S. A., Harrison R. J., Robinson P., Langenhorst F., Nanoscale haematite–ilmenite lamellae in massive ilmenite rock: An example of ‘lamellar magnetism’ with implications for planetary magnetic anomalies. Geophys. J. Int. 151, 890–912 (2002). [Google Scholar]
  • 21.Kasama T., McEnroe S. A., Ozaki N., Kogure T., Putnis A., Effects of nanoscale exsolution in hematite–ilmenite on the acquisition of stable natural remanent magnetization. Earth Planet. Sci. Lett. 224, 461–475 (2004). [Google Scholar]
  • 22.McEnroe S. A., Langenhorst F., Robinson P., Bromiley G., Shaw C., What is magnetic in the lower crust? Earth Planet. Sci. Lett. 226, 175–192 (2004). [Google Scholar]
  • 23.McEnroe S. A., Carter-Stiglitz B., Harrison R. J., Robinson P., Fabian K., McCammon C., Magnetic exchange bias of more than 1 Tesla in a natural mineral intergrowth. Nat. Nanotech. 2, 631–634 (2007). [DOI] [PubMed] [Google Scholar]
  • 24.Nagata T., Akimoto S., Uyeda S., Origin of reverse thermo-remanent magnetism of igneous rocks. Nature 172, 630–631 (1953). [Google Scholar]
  • 25.Nagata T., Uyeda S., Production of self-reversal of thermo-remanent magnetism by heat treatment of ferromagnetic minerals. Nature 177, 179–180 (1956). [Google Scholar]
  • 26.Ishikawa Y., Syono Y., Order-disorder transformation and reverse thermo-remanent magnetism in the FeTiO3–Fe2O3 system. J. Phys. Chem. Solid 24, 517–528 (1963). [Google Scholar]
  • 27.Haggerty S. E., Sautter V., Ultradeep (greater than 300 kilometers), ultramafic upper mantle xenoliths. Science 248, 993–996 (1990). [DOI] [PubMed] [Google Scholar]
  • 28.Coe R. S., Egli R., Gilder S. A., Wright J. P., The thermodynamic effect of nonhydrostatic stress on the Verwey transition. Earth Planet. Sci. Lett. 319-320, 207–217 (2012). [Google Scholar]
  • 29.Nishio-Hamane D., Zhang M., Yagi T., Yanming M., High-pressure and high-temperature phase transitions in FeTiO3 and a new dense FeTi3O7 structure. Am. Mineral. 97, 568–572 (2012). [Google Scholar]
  • 30.McEnroe S. A., Robinson P., Church N., Purucker M., Magnetism at depth: A view from an ancient continental subduction and collision zone. Geochem. Geophys. Geosyst., 1123–1147 (2018). [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Schult A., Effect of pressure on the Curie temperature of titano-magnetites [(1-x)Fe3O4-xTiFe2O4]. Earth Planet. Sci. Lett. 10, 81–86 (1970). [Google Scholar]
  • 32.Kozlenko D. P., Dubrovinsky L. S., Kichanov S. E., Lukin E. V., Cerantola V., Chumakov A. I., Savenko B. N., Magnetic and electronic properties of manganite across the high pressure anomaly. Sci. Rep. 9, 4464 (2019). [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.C. K. Shearer, P. C. Hess, M. A. Wieczorek, L. E. Elkins-Tanton, C. R. Neal, I. Antonenko, R. M. Canup, A. N. Halliday, T. L. Grove, B. H. Hager, D.-C. Lee, W. Wiechert, Thermal and magnetic evolution of the Moon, in New Views of the Moon, Rev. Mineral, B. L. Jolliff, Ed. (Mineral. Soc. Am., 2006), vol. 60, pp. 365–518. [Google Scholar]
  • 34.Acuña M. H., Connerney J. E. P., Ness N. F., Lin R. P., Mitchell D., Carlson C. W., McFadden J., Anderson K. A., Rème H., Mazelle C., Vignes D., Wasilewski P., Cloutier P., Global distribution of crustal magnetization discovered by the Mars global surveyor MAG/ER experiment. Science 284, 790–793 (1999). [DOI] [PubMed] [Google Scholar]
  • 35.Connerney J. E. P., Acuña M. H., Wasilewski P., Ness N. F., Rème H., Mazelle C., Vignes D., Lin R. P., Mitchell D. L., Cloutier P., Magnetic lineations in the ancient crust of Mars. Science 284, 794–798 (1999). [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Figs. S1 to S6

Table S1

Click here for additional data file. (1.6MB, pdf)

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