Quantum contribution to magnetotransport in weak magnetic fields and negative longitudinal magnetoresistance

Large magnetoresistance with low saturation fields in magnetic/magnetic superlattices

Ni/Co multilayers grown by molecular beam epitaxy are found to exhibit a magnetoresistance AR/R at liquid helium temperature as large as 8.2%, with saturation fields AH-22 Oe and a sensitivity (AR/R)/(2AH)=O. 19% Oe-‘. The highest room temperature sensitivity obtained to date in this system is 0.18% Oe-’ and at 4.2 K is 0.29% Oe-‘. This demonstrates that high values of the sensitivity can be ac...

Bats Respond to Very Weak Magnetic Fields

How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths oc...

Domain structure and magnetotransport in epitaxial colossal magnetoresistance thin films

Our studies of compressively strained La0.7Sr0.3MnO7 ~LSMO! thin films reveal the importance of domain structure and strain effects in the magnetization reversal and magnetotransport. Normal and grazing incidence x-ray diffraction indicate that the compressive strain on these LSMO thin films on ~100! LaAlO3 is not completely relaxed up to thicknesses on the order of 1000 Å. The effect of the co...

Quantum Systems in Weak Gravitational Fields

Negative Magnetoresistance of Granular Metals in a Strong Magnetic Field

The magnetoresistance of a granular superconductor in a strong magnetic field that destroys the gap in each grain is considered. It is assumed that the tunneling between grains is sufficiently large such that all conventional effects of localization can be neglected. A nontrivial sensitivity to the magnetic field comes from superconducting fluctuations leading to the formation of virtual Cooper...