Impedance behavior of spin-valve transistor

Abstract

The magnetoimpedance (MZ) effect of the pseudo-spin-valve transistor (PSVT) was investigated at room temperature in the frequency ranged from 100 Hz to 15 MHz. The PSVT can be regarded as a complex combination of resistors, inductors, and capacitors, while the impedance (Z) consists of a real part, the resistance (R), and an imaginary part, the reactance (X). Besides, all these components exhibit magnetic hysteresis. It is due to the frequency dependent behavior that R does not reach a minimum at the resonant frequency (f(r)). The frequency dependences of MZ and MX ratios cross zero at f(x)=6.5 MHz and at f(r)=3.65 MHz, respectively. The shape of magnetoreactance (MX) loop is reverse to the magnetoresistance (MR) loop; furthermore, MX ratio changes sign from negative at f < f(r) to positive at f>f(r). The MZ loop also reverses shape and sign after crossing f(x). For instance, the MZ loop with a ratio of 0.077% at 6 MHz switches to -0.086% and -0.125% at 7 and 8 MHz, respectively. (C) 2006 American Institute of Physics.