D. Dahlberg

University of Minnesota Duluth, Duluth, Minnesota, United States

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Publications (2)4.42 Total impact

  • G. Kote, L. Hedman, D. Dahlberg, K. V. Rao
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    ABSTRACT: Magnetic properties of amorphous (Ni 1-x Mn x ) 7 5 P 1 6 B 6 Al 3 alloys have been probed using transverse magnetoresistance (in fields up to 9 T), and susceptibility measurements (in low fields using a SQUID magnetometer, and at high fields of up to 1 T using a Faraday balance), in the temperature range 4–300 K. Low field susceptibility data show a spin‐glass type of behavior for alloys with x≫0.1. At low concentrations of Mn the spin freezing temperature T f is found to increase linearly with x. A maximum value of T f =61 K is observed for the alloy with x=0.6. Analyses of the high field susceptibility data indicates that in this amorphous matrix Ni does not carry a moment. The transverse magnetoresistance is found to be negative at all temperatures and applied fields, and for T≫2T f the magnetoresistance is found to have a quadratic field dependence.
    Journal of Applied Physics 04/1984; · 2.21 Impact Factor
  • D. Dahlberg, K. V. Rao, K. Fukamichi
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    ABSTRACT: A remarkable feature in amorphous Fe 1-x Zr x alloys is that for Fe concentrations greater than 90 at %, the ferromagnetic transition temperature T C decreases with increasing Fe concentration. In addition, alloys containing 93–90 at % Fe are found to show a spin‐glass‐like behavior at low temperatures, i.e., below T C . The electrical resistivity of these alloys shows a minimum at roughly the Curie temperature. We have measured the transverse magnetoresistance of Fe 9 1 Zr 9 , and Fe 9 0 Zr 1 0 alloys from 4 to 300 K in applied magnetic fields as large as 9 T. We find that (1) the field derivative of the magnetoresistance is positive at all temperatures in applied fields larger than 0.1 T; (2) a maximum occurs in the magnetoresistance at roughly the Curie temperature; (3) below the Curie temperature a small negative low‐field magnetoresistance develops which increases with decreasing temperature. These results indicate that the resistance minimum which occurs around the Curie temperature for these alloys is due to the coherent exchange scattering by the Fe moments, and is not associated with a Kondo mechanism as previously proposed.
    Journal of Applied Physics 04/1984; · 2.21 Impact Factor