Magnetic tunnel junctions with voltage tunable interlayer coupling for memory and sensor applications
View Patent ↗Various examples are provided for magnetic tunnel junctions and applications thereof. In one example, a magnetic tunnel junction (MTJ) device includes a first ferromagnetic (FM) layer; a gadolinium oxide (GdO X ) tunnel barrier disposed on the first ferromagnetic layer; and a second FM layer disposed on the GdO X tunnel barrier. In another example, a perpendicular MTJ (pMTJ) device includes a first layer including a magnetic material; a tunnel barrier disposed on the first layer to form the pMTJ; and a second layer including the magnetic material, the second layer disposed on the tunnel barrier.
1. A magnetic tunnel junction (MTJ) device, comprising:
a first ferromagnetic (FM) layer, where the first FM layer is a fixed FM layer consisting of a single layer of FM material having a first thickness;
a gadolinium oxide (GdO X ) tunnel barrier having a first side disposed on a first side of the first ferromagnetic layer, where the GdO X tunnel barrier comprises Gd 2 O 3 , and a resistance state of the MTJ device is controllable at room temperature;
a first buffering layer disposed on a second side of the first FM layer opposite the GdO X tunnel barrier;
a second FM layer, where the second FM layer is a free FM layer consisting of a single layer of FM material having a second thickness greater than the first thickness, the second FM layer having a first side disposed on a second side of the GdO X tunnel barrier, where the FM material of the second layer has the same material composition as the FM material of the first layer; and
a second buffering layer disposed on a second side of the second FM layer opposite the GdO x tunnel barrier.
2. The MTJ device of claim 1 , wherein the GdO X tunnel barrier between the first and second FM layers forms a perpendicular MTJ (pMTJ).
3. The MTJ device of claim 1 , wherein application of a positive voltage pulse across the free and fixed layers under zero magnetic field sets the MTJ device to a non-volatile low resistance state.
4. The MTJ device of claim 1 , wherein application of a negative voltage pulse across the free and fixed layers under zero magnetic field sets the MTJ device to a non-volatile high resistance state.
5. The MJT device of claim 4 , wherein the negative voltage pulse establishes antiferromagnetic (AFM) coupling between the free and fixed layers.
6. The MTJ device of claim 1 , wherein a thickness of the GdO X tunnel barrier is in a range from about 1 nm to about 3.5 nm.
7. The MTJ device of claim 1 , wherein the first and second FM layers comprise cobalt iron boron (CoFeB).
8. The MTJ device of claim 1 , wherein the thickness of the first FM layer is in a range from about 0.7 nm to about 0.9 nm and the thickness of the second FM layer is in a range from about 1.5 nm to about 1.6 nm.
9. A sensor comprising the MTJ device of claim 1 , where the sensor detects a magnetic field.
10. A memory storage system comprising the MTJ device of claim 1 .
11. The MTJ device of claim 1 , wherein a thickness of the GdO X tunnel barrier is greater than 2 nm.