Many particle-physics models that extend the standard model predict the existence of long-range spin-spin interactions. We propose an approach that uses the Earth as a polarized spin source to investigate these interactions. Using recent deep-Earth geophysics and geochemistry results, we create a comprehensive map of electron polarization within the Earth induced by the geomagnetic field. We examine possible long-range interactions between these spin-polarized geoelectrons and the spin-polarized electrons and nucleons in three laboratory experiments. By combining our model and the results from these experiments, we establish bounds on torsion gravity and possible long-range spin-spin forces associated with the virtual exchange of either spin-one axial bosons or unparticles.

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The specific heat of the colossal magnetoresistance material Nd 0.67 Sr 0.33 MnO 3 is reported for 0.35рT р280 K, Hϭ0 and 1рTр120 K, Hϭ9 T. The results include a Schottky-like specific-heat anomaly for the Nd ordering, an ''attenuation'' of the Mn ordering anomaly, and a T-dependent ''linear term,'' ␥(T)T. This unusual combination of features is interpreted as arising from an interaction between the Nd and Mn spin systems. The expected magnetic entropy is recovered only if a contribution from the ␥(T)T term is included.

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