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Universal Properties of Linear Magnetoresistance Donald Heiman , Northeastern University, DMR 0907007.

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  1. Universal Properties of Linear MagnetoresistanceDonald Heiman, Northeastern University, DMR 0907007 Linear magnetoresistance occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, we found that the magnitude of the linear magnetoresistance (LMR) is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of classical LMR that can be applied to other material systems. H. Johnson, et.al., Phys. Rev. B 82, 085202 (2010.) Magnetoresistance (MR) increases with field; slope of MR is proportional to carrier mobility over large temperature range.

  2. Undergraduate ResearchUniversal Properties of Linear Magnetoresistance Donald Heiman, Northeastern University, DMR 0907007 This research on the Linear Magnetoresistance effect has been completed by several undergraduate students. Two of these undergraduates (Hannah Johnson and Steve Bennett) are coauthors on a paper that was published in the Physical Review, and Hannah Johnson was the lead author. Hannah Johnson was responsible for the magnetic and conductivity measurements. Steve Bennett was responsible for synthesizing the films in our molecular beam epitaxy (MBE) growth apparatus and characterizing the nanostructures with the scanning electron microscope (SEM). The project was in collaboration with a graduate student, RadhikaBarua, and Prof. Laura Lewis in Chemical Engineering . The lead researcher on this project, Hannah Johnson, carried out the work as an undergraduate Co-op student partially supported by an NSF-REU supplement. H. Johnson, S.P. Bennett, R. Barua, L.H Lewis, and D. Heiman, Phys. Rev. B 82, 085202 (2010.)

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