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 100Hzto15MHz. 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 (fr). The frequency dependences of MZ and MX ratios cross zero at fx=6.5MHz and at fr=3.65MHz, respectively. The shape of magnetoreactance (MX) loop is reverse to the magnetoresistance (MR) loop; furthermore, MX ratio changes sign from negative at f<fr to positive at f>fr. The MZ loop also reverses shape and sign after crossing fx. For instance, the MZ loop with a ratio of 0.077% at 6MHz switches to −0.086% and −0.125% at 7 and 8MHz, respectively.