# US 9,437,655 B2 · Magnetic tunnel junction with superlattice barriers

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- Number: US 9,437,655 B2
- Document ID: US9437655B2
- Status: Granted
- Kind: B2
- Application number: 14/460,358
- Filed: 2014-08-15
- Published: 2015-07-30
- Granted: 2016-09-06
- Earliest claimed: 2014-01-24
- Assignees: National Taiwan University
- Applicants: National Taiwan University
- Inventors: Wen-Jeng Hsueh; Chang-Hung Chen
- Web page: https://patentgrep.com/patent/US9437655B2

## CPC

- H10B 61/22: {of the field-effect transistor [FET] type}
- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- H10N 50/10: Magnetoresistive devices
- H10B: ELECTRONIC MEMORY DEVICES
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A magnetic tunnel junction is provided. The magnetic tunnel junction can enhance the tunnel magnetoresistance ratio and a device including the magnetic tunnel junction. The magnetic tunnel junction includes: a pinned layer; a free layer; and a superlattice barrier, the barrier configured between the pinned layer and the free layer. The magnetic tunnel junction may be a series or parallel connection of the above-mentioned basic form. The device including a magnetic tunnel junction may be a magnetic random access memory bit cell, a magnetic tunnel junction transistor device, a magnetic field sensor, etc.

## Claims

### Claim 1

A magnetic tunnel junction, comprising:
a pinned layer;
a free layer; and
a superlattice barrier configured between the pinned layer and the free layer, wherein the superlattice barrier includes at least two multilayer cells and has a leftmost layer and a rightmost layer, the at least two multilayer cells are horizontally stacked, each of the at least two multilayer cells includes at least one insulator layer and at least one conductor layer, the leftmost layer is one of an insulator layer and a conductor layer, and the rightmost layer is the other one of the insulator layer and the conductor layer.

### Claim 2 (depends on 1)

The magnetic tunnel junction as claimed in claim 1, wherein either one of the pinned layer and the free layer is one of a ferromagnetic material and a semiconductor material.

### Claim 3 (depends on 1)

The magnetic tunnel junction as claimed in claim 1, wherein when the total number of the at least one conductor layer and the total number of the at least one insulator layer are both 1, the at least one conductor layer and the at least one insulator layer are horizontally stacked, and when at least one of the total number of the at least one conductor layer and the total number of the at least one insulator layer is no smaller than 2, the stacked at least one conductor layer and the stacked at least one insulator layer are horizontally stacked.

### Claim 4 (depends on 1)

The magnetic tunnel junction as claimed in claim 1, further comprising a buffer layer, wherein the buffer layer is located in one selected from a position group consisting of being between the superlattice barrier and the pinned layer, between the superlattice barrier and the free layer, and between the at least two multilayer cells.

### Claim 5 (depends on 1)

The magnetic tunnel junction as claimed in claim 1, wherein the pinned layer has a first magnetization direction, the first magnetization direction extends along a line on the plane of the pinned layer, and the magnetization direction of the free layer is one of being the same as and opposite to the first magnetization direction.

### Claim 6 (depends on 1)

The magnetic tunnel junction as claimed in claim 1, wherein the pinned layer has a first magnetization direction extending along a line perpendicular to the plane of the pinned layer, and the magnetization direction of the free layer is one of being the same as and opposite to the first magnetization direction.