Controlling and modifying sensing properties of tunneling magnetoresistance sensors by voltage controlled magnetic anisotropy

Abstract

We present investigation on sensing characteristics dependence on bias voltage in CoFeB/MgO/CoFeB based tunneling magnetoresistance sensors designed to have perpendicular magnetic anisotropy in a sensing layer. The voltage controlled magnetic anisotropy effect was used to modify the perpendicular magnetic anisotropy. The modulation of the anisotropy is achieved by changing bias voltage polarity and strength. The change in the magnetic anisotropy influences spin dependent tunneling current during magnetic field sweeping. As a result of the current modification sensitivity, sensing range, nonlinearity and hysteresis of the sensors changed with the bias voltage strength and polarity. The sensitivity, sensing range, nonlinearity and hysteresis show linear dependence on the bias voltage. Under bias reversal between +1V and -1 V, the sensing properties changed more than a factor of 2. The linear dependence of the sensing characteristics and significant changed upon bias polarity reversal indicate potential of their control and modification by bias voltage polarity and strength. The use of voltage controlled perpendicular magnetic anisotropy in TMR sensors design creates new possibilities in development and applications of the TMR sensors with bias voltage controlled sensing properties.