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US 8,274,818 B2Granted
Magnetoresistive element, magnetic memory cell and magnetic random access memory using the same
AssigneesTohoku University, Hitachi, Ltd.
InventorsHideo Ohno, Shoji Ikeda, Young Min Lee, Jun Hayakawa
Life of this patent
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Abstract
Provided is a high-speed and ultra-low-power-consumption nonvolatile memory having a high temperature stability at a zero magnetic field. In a tunnel magnetoresistive film constituting a nonvolatile magnetic memory that employs a writing method using a spin-transfer torque, an insulating layer and a nonmagnetic conductive layer are stacked above a ferromagnetic free layer.
Claims24
A magnetoresistive element comprising;
- a tunnel magnetoresistive film including:
- a ferromagnetic free layer;
- a ferromagnetic pinned layer;
- a first insulating layer formed between the ferromagnetic free layer and the ferromagnetic pinned layer;
- a second insulating layer formed on a surface, opposite to a surface on the first insulating layer side, of the ferromagnetic free layer;
- and
- a nonmagnetic conductive layer formed on a surface, opposite to a surface on the ferromagnetic free layer side, of the second insulating layer, wherein the tunnel magnetoresistive film is configured so that:
- when a current is caused to pass in a thickness direction of at least the nonmagnetic conductive layer, the second insulating layer, the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer, the magnetization of the ferromagnetic free layer is reversed, and
- when a second current is caused to pass in a thickness direction of at least the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer, a magnetization direction of the ferromagnetic free layer is detected, and
- wherein the thickness of the second insulating layer is equal to or greater than 0.5 nm, and
- wherein the thickness of the first insulating layer is greater than the thickness of the second insulating layer.
8 more elements
A magnetic memory cell comprising:
- a tunnel magnetoresistive film including:
- a ferromagnetic free layer;
- a ferromagnetic pinned layer;
- a first insulating layer formed between the ferromagnetic free layer and the ferromagnetic pinned layer;
- a second insulating layer formed on a surface, opposite to a surface on the first insulating layer side, of the ferromagnetic free layer;
- and
- a nonmagnetic conductive layer formed on a surface, opposite to a surface on the ferromagnetic free layer side, of the second insulating layer,
- a means for causing a write current to pass in a thickness direction of at least the nonmagnetic conductive layer, the second insulating layer, the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer when writing information;
- a means for causing a read current to pass in a thickness direction of at least the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer when reading information;
- and
- a switching element that carries out on-off control of the write current and the read current,
- wherein the thickness of the second insulating layer is equal to or greater than 0.5 mm, and
- wherein the thickness of the first insulating layer is greater than the thickness of the second insulating layer.
10 more elements
A magnetic random access memory comprising:
- a memory cell group, in which a plurality of magnetic memory cells are arranged in a two-dimensional array, each of memory cells including:
- a magnetoresistive element;
- a means for causing a write current and a read current to pass into the magnetoresistive element;
- and a switching element that carries out on-off control of the write current and the read current;
- and
- a selector that selects a desired magnetic memory cell in the memory cell group, wherein
- the magnetoresistive element includes:
- a tunnel magnetoresistive film including:
- a ferromagnetic free layer;
- a ferromagnetic pinned layer;
- a first insulating layer formed between the ferromagnetic free layer and the ferromagnetic pinned layer;
- a second insulating layer formed on a surface, opposite to a surface on the first insulating layer side, of the ferromagnetic free layer;
- and
- a nonmagnetic conductive layer formed on a surface, opposite to a surface on the ferromagnetic free layer side, of the second insulating layer,
- a means for causing the write current to pass in a thickness direction of at least the nonmagnetic conductive layer, the second insulating layer, the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer;
- and
- a means for causing the read current to pass in a thickness direction of at least the ferromagnetic free layer, the first insulating layer, and the ferromagnetic pinned layer,
- wherein the thickness of the second insulating layer is equal to or greater than 0.5 mm, and
- wherein the thickness of the first insulating layer is greater than the thickness of the second insulating layer.
16 more elements
Dependencies are inferred from the claim text.