RU2635330C1 - Magnetic field converter with increased sensitivity on anisotropic thin-film magnetoresistors (versions) - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: magnetic field converter consists of four magnetoresistors made on a substrate with an oxidized layer in the form of thin-film magnetic strips with shunting strips of a conductive material at an angle of 45° to the longitudinal axis of the magnetoresistors included in the bridge circuit using the thin-film conductors, where the magnetoresistors at the locations of the shunting strips on them have a shape completely replicating the shape of the shunting strip.

EFFECT: providing the possibility of increasing the sensitivity to the magnetic field.

2 cl, 5 dwg

Description

The invention relates to the field of automation and magnetometry and can be used to register constant and variable magnetic fields.

Known devices for recording a magnetic field, which are thin-film anisotropic magnetoresistors included in the bridge circuit (US 8884610, US 8547087 RU 2495514 C1, 10.10.2013, US 5055786 A, 08.10.1991).

The closest by design features the claimed is a device that is a magnetoresistor in the form of strips of magnetic material, which are applied shunt strips of conductive material at an angle of 45 ° to the longitudinal axis of the strips (RU 2533747 C1, 11/20/2014). The disadvantage of this device is its relatively low sensitivity to the magnetic field due to the fact that the magnetization at the edges of the magnetic strip is oriented at an angle to the current lines much less than 45 °, due to the geometric arrangement of the shunt strips, i.e. these areas respond weaker to the magnetic field than the central regions.

The technical result of this technical solution is to increase the sensitivity to the magnetic field.

The indicated result is achieved in that the shape of the magnetic strip on which the shunt strip is located completely repeats the shape of the shunt strip. As a result, the distribution of magnetization in the magnetic layer differs significantly from the uniform distribution in the classical magnetoresistor. In particular, in the regions of the magnetic layer under the shunt strip, magnetization distribution inhomogeneities occur, leading to a change in the distribution of magnetization in the regions of the magnetic strip between the shunt strips and, in particular, at the edges of the magnetic strip. As a result, the angle between the magnetization vector and streamlines becomes close to 45 ° over a larger area of the magnetic strip. In this regard, a large region of the magnetic strip between the shunts will effectively respond to a magnetic field, which will increase the sensitivity of the magnetoresistor and the transducer as a whole. The sensitivity (S) of the magnetoresistive converter is determined by the expression

,

,

where ΔR is the change in resistance in a magnetic field,

R is the resistance of the magnetoresistor,

N to is the anisotropy field.

In FIG. Figure 1 shows a graph of the resistance of a magnetoresistor obtained as a result of a calculation based on a micromagnetic model that takes into account the inhomogeneous distribution of magnetization, which shows that for a structure with a magnetic layer repeating the shape of a shunt strip, the change in resistance is large compared to the classical structure, those. graphs have a different slope. In accordance with (1), the sensitivity S of a converter with such a structure will also be greater than the classical one.

In FIG. 2 shows the transfer characteristics for a classic magnetoresistor and claimed with the same geometry. Characteristic 4 has a greater slope, which indicates a greater sensitivity of the device.

In FIG. 3 shows the inventive device. The magnetoresistive layer 1 is made in a configuration that completely matches the configuration of the conductive layer 2, and the entire area under the shunt strips is filled with magnetic material.

In FIG. 4 shows a second embodiment of the inventive device. On the magnetoresistive layer 1, made in a configuration that completely matches the configuration of the conductive layer 2, a layer of dielectric material 3 is deposited, in which windows are made in the form of shunt conductors, in which, in turn, shunt conductors 2 are made.

Technically, the device is implemented as follows. A 0.03 μm thick permalloy layer (80% Ni20% Fe) was sprayed onto a silicon wafer on which an insulating layer had previously been formed, on which a pattern in the form of strips with regular transverse extensions in the form of shunts was formed by photolithography. Then a layer of aluminum was sprayed, on which a pattern of conductive elements in the form of transverse shunts was also formed by photolithography. The manufactured device had the following topological dimensions: the width of the magnetic strip was 10 μm, the width of the shunt strip was 6 μm, the distance between the shunt stripes was 10 μm.

In FIG. 5 shows the transfer characteristic of the device, where, for comparison, the characteristic of a classical device with the same topological dimensions is shown. It is clearly seen that the characteristic of the claimed device has a slope significantly higher than the slope of the characteristics of a classical device, which indicates a greater sensitivity of the claimed device. The sensitivity calculation on the linear section of the characteristic gives the following values: for the inventive device - 11.3 mV / V / kA / m, while for the classical one - only 4.2 mV / V / kA / m. Thus, the fact of sensitivity increase by more than 2.5 times is confirmed.

Claims (2)

1. The magnetic field Converter, consisting of four magnetoresistors made on a substrate with an oxidized layer in the form of thin-film magnetic strips with shunt strips of conductive material at an angle of 45 ° to the longitudinal axis of the magnetoresistors included in the bridge circuit using thin-film conductors, characterized in that magnetoresistors at the locations of the shunt strips on them have a shape that completely repeats the shape of the shunt strip. 2. A magnetic field transducer consisting of four magnetoresistors made on a substrate with an oxidized layer in the form of thin-film magnetic strips with shunt strips of conductive material at an angle of 45 ° to the longitudinal axis of the magnetoresistors included in the bridge circuit using thin-film conductors, characterized in that an insulating layer is applied to the magnetoresistors, in which windows are made in the form of a shunt strip, on which a layer of conductive material is applied, from which, in turn, the shunt is made strips placed in the windows of the insulating layer.

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