Magnetoresistive effect oscillator

Patent metadata

Field	Value
Publication number	US-9762182-B2
Application number	US-201615098617-A
Country	US
Kind code	B2
Filing date	Apr 14, 2016
Priority date	Apr 15, 2015
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A magnetoresistive effect oscillator executes a first step of applying a current, which has a first current density larger than a critical current density J O for oscillation, to a magnetoresistive effect element for a time T P , and then executes a second step of applying a current, which has a second current density J S smaller than the first current density and not smaller than the critical current density J O for oscillation, to the magnetoresistive effect element. The following formulae (1), (2) and (3), or the following formulae (1) and (4) are satisfied on an assumption that an average value of the first current density during the time T P in the first step is J P , a critical current density for magnetization reversal of the magnetoresistive effect element is J R , and a magnetization reversal time of the magnetoresistive effect element is T R :

0.1
×

T
R

⁡

(

J
R

-

J
O

)

J
p

-

J
S

<

T
p

<

0.9
×

T
R

⁢

J
R

-

J
O

J
S

-

J
O

(
1
)

T
P

<

T
R

⁡

(

J
R

-

J
O

)

J
P

-

J
O

(
2
)

J
R

≤

J
P

(
3
)

J
P

<

J
R

.

(
4
)

First claim

What is claimed is:

1. A magnetoresistive effect oscillator comprising:
a magnetoresistive effect element including a first magnetic layer, a second magnetic layer, and a spacer layer sandwiched between the first magnetic layer and the second magnetic layer; and
a current applying unit that applies a current to the magnetoresistive effect element,
wherein the current applying unit executes a first step of applying a current, which has a first current density larger than a critical current density J O for oscillation of the magnetoresistive effect element, to the magnetoresistive effect element for a time T P ,
the current applying unit executes, after the first step, a second step of applying a current, which has a second current density J S smaller than the first current density and not smaller than the critical current density J O for oscillation, to the magnetoresistive effect element such that the magnetoresistive effect element oscillates at a predetermined frequency, and
the following formulae (1), (2) and (3), or the following formulae (1) and (4) are satisfied on an assumption that an average value of the first current density during the time T P in the first step is J P , a critical current density for magnetization reversal of the magnetoresistive effect element is J R , and a magnetization reversal time of the magnetoresistive effect element is T R :

0.1
×

T
R

⁡

(

J
R

-

J
O

)

J
p

-

J
S

<

T
p

<

0.9
×

T
R

⁢

J
R

-

J
O

J
S

-

J
O

(
1
)

T
p

<

T
R

⁡

(

J
R

-

J
O

)

J
P

-

J
O

(
2
)

J
R

≤

J
P

(
3
)

J
P

<

J
R

.

(
4
)

2. The magnetoresistive effect oscillator according to claim 1 , wherein the following formula (5) is satisfied:

0.25
×

T
R

⁡

(

J
R

-

J
O

)

J
p

-

J
S

<

T
p

<

0.75
×

T

Assignees

• Tdk Corp

Inventors

• Suzuki Tsuyoshi
• Suzuki Eiji

Classifications

• H01F10/26

  characterised by the substrate or intermediate layers {(H01F10/06 and H01F10/32 take precedence)} · CPC title

• H03B15/006 Primary

  using spin transfer effects or giant magnetoresistance · CPC title

• H01F10/3286

  Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy · CPC title

• H01F10/324

  Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer · CPC title

• H03B5/1206

  using multiple transistors for amplification · CPC title