Unveiling the Magnetic and Structural Properties of Hydrohematite : A Potential Water-Bearing Mineral on the Surface of Mars

Author

Abdullah Al Maruf, Dartmouth CollegeFollow

Date of Award

Summer 8-15-2024

Document Type

Thesis (Master's)

Department or Program

Earth Sciences

First Advisor

Sarah Slotznick

Second Advisor

Geoffroy Hautier

Abstract

Hematite (α-Fe₂O₃) is one of the most prevalent iron oxides in sedimentary rocks and on the surface of Mars. Recent studies suggest that natural "hydrohematite" exists, wherein hematite accommodates cations through compensation at the Fe³⁺–site, forming –OH bonds (i.e., structural water), with important implications for water in arid planetary environments. We present a detailed magnetic characterization to elucidate the magnetic response of H–doping on these samples, corroborating the results with first-principles calculations. First-order reversal curves show a sharp diagonal wing due to triaxial basal plane anisotropy. Low-temperature cooling experiments show the complete suppression of the Morin transition (T_M) down to 3 K, as opposed to at for pure hematite. The anisotropy energy calculations using density functional theory reveal significantly higher anisotropies between the in-plane and the out-of-plane spin orientation with substitutionally H–doped hematite a.k.a. hydrohematite, which would cause the depression observed experimentally. These results may provide a more comprehensive and fundamental understanding of natural hydrohematite and its formation and could serve as a blueprint for detecting this mineral on Mars via rover data or sample return.

Recommended Citation

Maruf, Abdullah Al, "Unveiling the Magnetic and Structural Properties of Hydrohematite : A Potential Water-Bearing Mineral on the Surface of Mars" (2024). Dartmouth College Master’s Theses. 186.
https://digitalcommons.dartmouth.edu/masters_theses/186