Abstract:
A magnetoresistive device having a favorable magnetic characteristic, and a magnetic memory device comprising this magnetoresistive device and having an excellent write/read characteristic are disclosed. A pair of ferromagnetic layer (magnetization pinned layer (5) and a magnetization free layer (7)) are opposed to each other, with an intermediate layer (6) interposed therebetween. The magnetoresistance can be varied by passing a current perpendicularly to the film surface. When the product of the resistivity multiplied by the film thickness of when a current is passed in the direction of the film thickness of the magnetization free layer (7) is defined as a normalized resistance, the normalized resistance of a magnetoresistive device (1) lies in the range from 2,000 to 10,000 Ωnm2. The magnetic memory device comprises such a magnetoresistive device (1), and a bit line and a word line between which the magnetoresistive device (1) is interposed in the direction of thickness.
Abstract:
[Object] To provide a memory apparatus capable of operating at high speed with less current and inhibiting a decrease in an amplitude of a readout signal. [Solving Means] A memory apparatus includes a memory device having a layer structure at least including a memory layer where a direction of magnetization is changed corresponding to information, a magnetic fixed layer where the direction of the magnetization is fixed, and an intermediate layer made of a non-magnetic body disposed between the memory layer and the magnetic fixed layer; current being capable of flowing in a lamination direction of the layer structure; a wiring for supplying the memory device with current flowing to the lamination direction; and a memory control unit for storing information by flowing standby current at a predetermined level to the memory device via the wiring to incline the magnetization direction of the memory layer from the direction perpendicular to a film surface and flowing recording current that is higher than the standby current via the wiring to change the magnetization direction of the memory layer.
Abstract:
PROBLEM TO BE SOLVED: To promote large storage capacity of a storage device while enhancing the operation stability thereof, by enhancing thermal stability of STT-MRAM storage elements furthermore, and allowing further miniaturization of the storage elements.SOLUTION: In an STT-MRAM storage element having a multi-layered ferri-pin structure where a magnetization fixed layer consists of a ferromagnetic layer and a non-ferromagnetic layer of at least two layers, the magnetic material in contact with an insulating layer in the magnetization fixed layer is composed of a CoFeB magnetic layer, the magnetic material not in contact with an insulating layer in the magnetization fixed layer is an alloy or a lamination structure using at least one kind of Pt group metal elements and ferromagnetic 3d transition metal elements out of 3d transition metal elements, respectively. Atomic concentration of the Pt group metal element is lower than that of the ferromagnetic 3d transition metal element. Consequently, multi-layered ferri-bonding strength is enhanced, and thermal stability of the storage element can be enhanced.
Abstract:
PROBLEM TO BE SOLVED: To reduce the number of times data with large write energy is written, which is unfavorable for the number of times a multi-level memory can be rewritten.SOLUTION: A multi-level memory includes a memory array unit including a plurality of memory cells each of which can store data values of two or more bits. The multi-level memory further includes a memory controller configured to perform: conversion in accordance with write data in the memory array unit by use of a conversion rule for converting a specific data value among the data values written in one memory cell into a data value other than the specific data value; and processing of writing the converted write data and a conversion rule identifier, which indicates the conversion rule of the conversion, into the memory array.
Abstract:
PROBLEM TO BE SOLVED: To provide a memory element and a memory device which can be operated by less current and in a high speed.SOLUTION: A memory element at least includes: a memory layer 14; a magnetization fixed layer 12; an intermediate layer 13 made of nonmagnetic material which is disposed between the memory layer 14 and the magnetization fixed layer 12; and a cap layer 15. In the memory layer, a first ferromagnetic layer 14i and a second ferromagnetic layer 14p are magnetically coupled to each other via a coupling layer 14c. The first ferromagnetic layer is in contact with the intermediate layer, the second ferromagnetic layer is in contact with the cap layer, one of the first ferromagnetic layer and the second ferromagnetic layer is an in-plane magnetization layer in which in-plane magnetization is dominant, and the other one is a perpendicular magnetization layer in which perpendicular magnetization is dominant, and each magnetization direction in the first ferromagnetic layer and the second ferromagnetic layer is inclined from a direction perpendicular to a film surface. Since the magnetization direction in the memory layer is inclined, amplitude increase in precession of the magnetization in the ferromagnetic layers begins promptly when a current in a direction perpendicular to the film surface is flowed into the memory element, thereby enabling inversion operation in a short time.