Novel effects in spin-dependent transport

Date & Time
31 July 2008 (Thur), 10:30 am - 12:00 am
6F seminar room, Sengen site
Prof. Renat Sabirianov
Dept. of Physics, Univ. of Nebraska / ISSP, Univ. of Tokyo
Novel effects in spin-dependent transport
Spin dependent transport in a synergistic combination with novel nanoscale magnetic and ferroelectric structures can be used to manipulate spin-dependent currents yielding new paradigms for device operation. I will discuss recent advances in spintronics concentrating on the discovery of new magnetoresistive phenomena: (1) ballistic anisotropic magnetoresistance (BAMR), a quantized change in the ballistic conductance of the nanowires and nanocontact with magnetization direction, (2) tunneling anisotropic magnetoresistance (TAMR) in magnetic break junctions, and (3) voltage induced magnetoresistance (MR) sign reversal. Transition metal oxides exhibit large changes in conductivity when an appropriate bias is applied, which make them promising for memory devices. The change in the MR associated with this transition has not been, however, explored, but may uncover fascinating physics. We have recently observed a MR sign reversal associated with the bias dependent on/off state in a Ni/NiO/CoNi/NiO/Co magnetic tunnel junction (MTJ) in nanowire geometry at T=1.5K. This behavior may be explained by a metal-insulator transition driven by a charge accumulation controlled by applied bias voltage.
Dr. Igor Solovyev