Large magnetoresistance and finite-size effect in electrodeposited bismuthlines

Finite-size effects in Bi lines of cross section 3 mu mxw, where w = 8-120 mum, have been studied. The lines were made by optical lithography followed by electrodeposition. At T = 5 K, the magnetoresistance (MR) decreases mon otonically with decreasing line width of the Bi films, from 44 000% at w = 120 mum to 4000% at w = 8 mum in a field of 50 kOe. The decrease of the MR with decreasing linewidth is due to a decrease of the size-limited effectiv e-mean-free path. At low temperatures, both the resistivity and the magneto resistivity show a strong dependence on w, whereas at room temperature, the y are independent of w. The MR at room temperature remains at about 230% fo r linewidths w = 8-120 mum at 50 kOe. This demonstrates that microstructure d Bi lines can be made for field-sensing applications without compromising their MR characteristics. (C) 2001 American Institute of Physics.