Low-noise magnetic-flux sensors based on the extraordinary magnetoresistance effect

Abstract

We report noise measurements on Au–InAs hybrid structures involving a high-mobility two-dimensional electron system. Such structures show the extraordinary magnetoresistance (EMR) effect. We find excellent noise performance at room temperature close to the Johnson noise, which is in particular important for a technical application. At 4.2 K and in a magnetic field of about 1 T the nonoptimized EMR device is found to exhibit a low magnetic flux noise, offering the perspective of sensor applications also in a high magnetic field and at cryogenic temperature.

Finite-Element Modelling and Analysis of Hall Effect and Extraordinary Magnetoresistance Effect

“…It is important to note that the fundamental principle of EMR is the change of the current path in the hybrid structure upon application of a magnetic field rather than the change of magnetoconductivity σ of either the semiconductor or the metal [4][5]. This effect has drawn much attention due to its potential advantages over other solid-state magnetic field sensors [6][7][8][9]. Noise is rather low in EMR devices, since they are made of nonmagnetic materials, and there is no contribution from magnetic noise as it is in contemporary tunnel magnetoresistance or giant magnetoresistance devices [10], and there is less thermal noise than in Hall sensors due to the lower resistance provided by the conducting shunt.…”

Hall effect enhanced low-field sensitivity in a three-contact extraordinary magnetoresistance sensor

“…Thus, in addition to a component d 4-2 resulting from the asymmetric EMR effect of common sensors, the output sensitivity of this device is enhanced by a component d [3][4] , which is caused by the Hall effect. The voltages V i-j measured between different electrodes are shown as a function of the magnetic field B in Fig.…”

“…2,3 This effect is utilized to implement sensors for the measurement of magnetic fields perpendicular to the device. [4][5][6] Experiments on the EMR effect were initially performed in a macroscopic composite Van der Pauw disk made of a semiconductor disk with a concentric metallic circular inhomogeneity embedded, and four electrodes were used to apply current and measure voltage ( Fig. 1(a)).…”

Importance of interface sampling for extraordinary resistance effects in metal semiconductor hybrids

“…In the latter, a uniaxial tensile stress applied parallel to the metal semiconductor interface is thought to reduce the interface resistance, thereby redirecting current into the metal and reducing the measured resistance. Since the change in resistance can be more than an order of magnitude larger than that measured in the semiconductor alone, EXX ͑XX= MR or PC͒ has been proposed for a number of applications in which a sensitive measure of magnetic field 3,4 or strain 2 is required.…”