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Abstract Some rock and soil samples exhibit significant loss of magnetic susceptibility (χ) with increasing applied field amplitude even at relatively low (10–100s of A/m) fields, a behavior which remains unexplained. Exceptionally strong negative field‐dependence of susceptibility (χHD) is present in sandstones and altered intermediate‐felsic igneous rocks in several cores from the northeastern Oklahoma subsurface. These same rocks also show elevated frequency‐dependence of susceptibility (χFD), with reasonable correlation ofχHDtoχFD, and frequency‐dependentχHD. Results from multiple characterization methods indicate that strongly negativeχHDin these rocks is linked to a yet‐unidentified phase which begins the approach to magnetic saturation in low fields (<1 mT/800 A/m), shows elevatedχFDto low temperatures, is unstable at high temperatures, possesses significant anisotropy of magnetic susceptibility, and becomes paramagnetic above ∼83°C. Clear associations with fluid alteration features indicate that this material may be highly relevant to rock alteration, diagenetic, and environmental studies.
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Magnetic Susceptibility of Andreev Bound States in Superfluid 3 He−B
Nuclear magnetic resonance measurements of the magnetic susceptibility of superfluid 3 He imbibed in anisotropic aerogel reveal anomalous behavior at low temperatures. Although the frequency shift clearly identifies a low-temperature phase as the 𝐵 phase, the magnetic susceptibility does not display the expected decrease associated with the formation of the opposite-spin Cooper pairs. This susceptibility anomaly appears to be the predicted high-field behavior corresponding to the Ising-like magnetic character of surface Andreev bound states within the planar aerogel structures.
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- Award ID(s):
- 2210112
- PAR ID:
- 10578489
- Publisher / Repository:
- American Physical Society
- Date Published:
- Journal Name:
- Physical Review Letters
- Volume:
- 131
- Issue:
- 4
- ISSN:
- 0031-9007
- Page Range / eLocation ID:
- 046001-6
- Subject(s) / Keyword(s):
- Impurities Aerogel Helium-3 superfluids Superfluids Nuclear magnetic resonance
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1103/PhysRevLett.131.046001
