Sign Reversal of Magnetoresistance in TbMn2Si2.

Temperature and field dependent magnetization and resistivity of TbMn2Si2 have been studied. Two first order magnetic transitions at Tc1= 52 K and Tc2= 64 K are observed in both the measurements. The rise in resistivity at Tc2 with decrease in temperature is attributed to large difference in the periodicity of magnetic and crystallographic lattice. Resistivity fits at low and relatively higher temperatures give good account of the data. These fits further suggest the role of spin fluctuations in the antiferromagnetic region. Magnetoresistance calculated from in-field resistivity data, up to 8 T, shows switching from positive to negative to positive values with temperature. [ABSTRACT FROM AUTHOR]