US 8,203,389 B1Granted

Field tunable spin torque oscillator for RF signal generation

AssigneeHeadway Technologies, Inc.

InventorsYuchen Zhou, Kunliang Zhang, Pokang Wang, Joe Smyth

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Abstract

A spin transfer oscillator (STO) device is disclosed with a giant magnetoresistive (GMR) junction comprising a magnetic resistance layer (MRL)/spacer/magnetic oscillation layer (MOL) configuration, and a MR sensor including a sensing layer/junction layer/reference layer configuration. MOL and sensing layer are magnetostatically coupled and separated by a conductive spacer. MRL has perpendicular magnetic anisotropy while MOL and sensing layer have a Mst (saturation magnetization×thickness) value within ±50% of each other. When a magnetic field is applied perpendicular to the planes of the MOL and a high density current flows from the conductive spacer to the MRL, a MOL oscillation state with a certain frequency is induced. Consequently, the sensing layer oscillates with a similar RF frequency and when a low density current flows across the MR sensor, an AC voltage signal is generated to determine the sensing layer frequency that can be varied by adjusting the applied field.

Claims21

Dependent claims

An RF signal generation device, comprising:

(a) a spin torque oscillator (STO) with a top surface and having at least one magnetic reference layer (MRL), a magnetic oscillation layer (MOL), and a first junction layer formed between the MRL and MOL;
(b) a magnetoresistive (MR) sensor having at least one magnetic sensing layer that is magnetostatically coupled with said MOL, a second magnetic reference layer with an in-plane pinned magnetization, and a second junction layer formed between the magnetic sensing layer and the second magnetic reference layer;
and
(c) a non-magnetic conductive spacer layer that is sandwiched between said MOL layer and said magnetic sensing layer wherein an oscillation state having an oscillation frequency is induced in said MOL when a magnetic field is applied to said STO and MR sensor in a direction perpendicular to the STO top surface concurrently with a first electric current flowing from said conductive spacer layer through the MOL to the MRL, and said magnetostatic coupling generates magnetic oscillation with an RF frequency in said magnetic sensing layer that produces a varying voltage across the MR sensor when a second electric current flows through the MR sensor layers.

1 more element

An RF signal generation structure, comprising:

(a) a spin torque oscillator (STO) with a top surface, bottom surface, and sidewall, and having at least one magnetic reference layer (MRL), a magnetic oscillation layer (MOL), and a first junction layer formed between the MRL and MOL;
(b) a magnetoresistive (MR) sensor having a top surface, bottom surface, and sidewall, and at least one magnetic sensing layer that is magnetostatically coupled with said MOL, a second magnetic reference layer with an in-plane pinned magnetization, and a second junction layer formed between the magnetic sensing layer and the second reference layer;
(c) a non-magnetic conductive spacer layer that contacts the STO top surface and the MR sensor bottom surface, and extends a certain distance from the STO and MR sensor sidewalls along an in-plane axis;
and
(d) a three electrical terminal configuration, comprising:
(1) a first electrical terminal connected to a portion of the non-magnetic spacer that extends along the in-plane axis;
(2) a second electrical terminal connected to the STO bottom surface;
and
(3) a third electrical terminal connected to the MR sensor top surface;
wherein an oscillation state having an oscillation frequency is induced in said MOL when a magnetic field is applied to said STO and MR sensor in a direction perpendicular to the STO top surface concurrently with a first electric current flowing from said first terminal to said second terminal, and said magnetostatic coupling generates magnetic oscillation with an RF frequency in said magnetic sensing layer that produces a varying voltage across the MR sensor when a second electric current flows between the second and third electrical terminals.

7 more elements

Dependencies are inferred from the claim text.