US2005136600A1PendingUtilityA1

Magnetic elements with ballistic magnetoresistance utilizing spin-transfer and an MRAM device using such magnetic elements

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Priority: Dec 22, 2003Filed: Dec 22, 2003Published: Jun 23, 2005
Est. expiryDec 22, 2023(expired)· nominal 20-yr term from priority
Inventors:Yiming Huai
H01F 10/3254H01F 41/305H01F 10/3295H01F 10/3227H01F 10/3272G11C 11/16B82Y 25/00H01F 10/3259B82Y 40/00H10N 50/10H10N 50/01
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Claims

Abstract

A method and system for providing a magnetic element is disclosed. The method and system include providing a pinned layer, a magnetic current confined layer, and a free layer. The pinned layer is ferromagnetic and has a first pinned layer magnetization. The magnetic current confined layer has at least one channel in an insulating matrix and resides between the pinned layer and the free layer. The channel(s) are ferromagnetic, conductive, and extend through the insulating matrix between the free layer and the pinned layer. The size(s) of the channel(s) are sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer. The free layer is ferromagnetic and has a free layer magnetization. Preferably, the method and system also include providing a second pinned layer and a nonmagnetic spacer layer between the second pinned layer and the free layer. In this aspect, the magnetic element is configured to allow the free layer magnetization to be switched using spin transfer.

Claims

exact text as granted — not AI-modified
1 . A magnetic element comprising: 
 a pinned layer having a pinned layer magnetization;    a free layer having a free layer magnetization;    a magnetic current confined layer residing between the pinned layer and the free layer, the magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic, conductive, and extending through the insulating matrix between the free layer and the pinned layer, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer.    
     
     
         2 . The magnetic element of  claim 1  wherein the at least one channel has a diameter of between one and three nanometers.  
     
     
         3 . The magnetic element of  claim 1  wherein the length is less than the mean free path of electrons in the at least one channel.  
     
     
         4 . The magnetic element of  claim 1  wherein the at least one channel further includes Ni, Co, Fe, and/or their alloys.  
     
     
         5 . The magnetic element of  claim 1  wherein the insulating matrix includes SiC and/or SiO.  
     
     
         6 . The magnetic element of  claim 1  wherein the free layer includes XB, XPt, XPd, and/or XCu, where X is Co or CoFe.  
     
     
         7 . A magnetic element comprising: 
 a pinned layer having a pinned layer magnetization;    a free layer having a free layer magnetization;    a magnetic current confined layer residing between the pinned layer and the free layer, the magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic, conductive, and extending through the insulating matrix between the free layer and the pinned layer, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer;    a second pinned layer having a second pinned layer magnetization; and    a nonmagnetic spacer layer residing between the free layer and the second pinned layer; and    wherein the magnetic element is configured to allow the free layer magnetization to be switched using spin transfer.    
     
     
         8 . The magnetic element of  claim 7  wherein the free layer, the second pinned layer, and the nonmagnetic spacer layer are configured to allow the free layer magnetization of the free layer to be switched using spin transfer.  
     
     
         9 . The magnetic element of  claim 7  wherein the free layer is a synthetic free layer.  
     
     
         10 . The magnetic element of  claim 9  wherein a portion of the first pinned layer adjacent to the magnetic current confined layer has a first magnetization, wherein a portion of the second pinned layer adjacent to the nonmagnetic spacer layer has a second magnetization substantially parallel to the first magnetization.  
     
     
         11 . The magnetic element of  claim 7  wherein the at least one channel further includes Ni, Co, Fe, and/or their alloys.  
     
     
         12 . The magnetic element of  claim 7  wherein the insulating matrix includes SiC and/or SiO.  
     
     
         13 . The magnetic element of  claim 7  wherein the free layer includes XB, XPt, XPd, and/or XCu, where X is Co or CoFe.  
     
     
         14 . A magnetic element comprising: 
 a pinned layer having a first pinned layer magnetization;    a first free layer having a first free layer magnetization;    a magnetic current confined layer residing between the pinned layer and the first free layer, the magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic, conductive, and extending through the insulating matrix between the first free layer and the pinned layer, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer; and    a second free layer having a second free layer magnetization, the second free layer being magnetostatically coupled to the first free layer;    a second pinned layer having a second pinned layer magnetization;    a nonmagnetic spacer layer residing between the second free layer and the second pinned layer;    wherein the second free layer is configured to allow the second free layer magnetization to be switched using spin transfer.    
     
     
         15 . The magnetic element of  claim 14  further comprising: 
 a conductive separation layer residing between the first free layer and the second free layer, the conductive spacer layer for ensuring that the first free layer and the second free layer are magnetostatically coupled.    
     
     
         16 . The magnetic element of  claim 14  wherein the at least one channel further includes Ni, Co, Fe, and/or their alloys.  
     
     
         17 . The magnetic element of  claim 14  wherein the insulating matrix includes SiC and/or SiO.  
     
     
         18 . The magnetic element of  claim 14  wherein the free layer includes XB, XPt, XPd, and/or XCu, where X is Co or CoFe.  
     
     
         19 . A method for providing a magnetic element comprising: 
 (a) providing a pinned layer having a first pinned layer magnetization;    (b) providing a magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic and conductive, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer; and    (c) providing a free layer having a free layer magnetization, the magnetic current confined layer residing between the pinned layer and the free layer, the at least one channel extending through the insulating matrix between the pinned layer and the free layer;    wherein the free layer is configured to allow the free layer magnetization to be switched using spin transfer.    
     
     
         20 . The method of  claim 19  wherein the at least one channel has a diameter of between one and three nanometers.  
     
     
         21 . The method of  claim 19  wherein the length is less than the mean free path of electrons in the at least one channel.  
     
     
         22 . The method of  claim 19  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) co-sputtering at least one ferromagnetic conductive material with at least one insulating matrix material, the at least one conducting channel being formed from the at least one ferromagnetic conductive material and the insulating matrix being formed from the at least one insulating matrix material.    
     
     
         23 . The method of  claim 19  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) forming the magnetic current confined layer using dry self-assembly.    
     
     
         24 . The method of  claim 19  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) providing at least one ferromagnetic conducting layer;    (b2) providing at least one insulating layer, the at least one insulating layer alternating with the at least one ferromagnetic conducting layer; and    (b3) providing a second ferromagnetic conducting layer such that each of the at least one insulating layer is sandwiched between a ferromagnetic conducting layer of the at least one ferromagnetic conducting layer and/or the second ferromagnetic conducting layer;    the at least one conducting channel being formed from the at least one ferromagnetic conducting layer and the second ferromagnetic conducting layer and the insulating matrix being formed from the at least one insulating layer.    
     
     
         25 . The method of  claim 24  wherein the current confined layer providing step (b) further includes the steps of: 
 (b4) annealing the magnetic element.    
     
     
         26 . A method for providing a magnetic element comprising: 
 (a) providing a pinned layer having a first pinned layer magnetization;    (b) providing a magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic and conductive, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the magnetic current confined layer; and    (c) providing a free layer having a free layer magnetization, the magnetic current confined layer residing between the pinned layer and the free layer, the at least one channel extending through the insulating matrix between the pinned layer and the free layer;    (d) providing a second pinned layer having a second pinned layer magnetization; and    (e) providing a nonmagnetic spacer layer residing between the free layer and the second pinned layer;    wherein the free layer is configured to allow the free layer magnetization to be switched using spin transfer.    
     
     
         27 . The method of  claim 26  wherein the free layer, the second pinned layer, and the nonmagnetic spacer layer are configured to allow the free layer magnetization of the free layer to be switched using spin transfer.  
     
     
         28 . The method of  claim 26  wherein the free layer providing step (a) further includes the step of: 
 (a1) providing a synthetic free layer.    
     
     
         29 . The method of  claim 28  wherein a portion of the pinned layer adjacent to the magnetic current confined layer has a first magnetization, wherein a portion of the second pinned layer adjacent to the nonmagnetic spacer layer has a second magnetization substantially parallel to the first magnetization.  
     
     
         30 . The method of  claim 26  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) co-sputtering at least one conductive material with at least one insulating matrix material, the at least one conducting channel being formed from the at least one conductive material and the insulating matrix being formed from the at least one insulating matrix material.    
     
     
         31 . The method of  claim 26  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) forming the magnetic current confined layer using dry self-assembly.    
     
     
         32 . The method of  claim 26  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) providing at least one ferromagnetic conducting layer;    (b2) providing at least one insulating layer, the at least one insulating layer alternating with the at least one ferromagnetic conducting layer; and    (b3) providing a second magnetic conducting layer such that each of the at least one insulating layer is sandwiched between a ferromagnetic conducting layer of the at least one magnetic conducting layer and/or the second ferromagnetic conducting layer;    the at least one conducting channel being formed from the at least one ferromagnetic conducting layer and the second ferromagnetic conducting layer and the insulating matrix being formed from the at least one insulating layer.    
     
     
         33 . The method of  claim 32  wherein the current confined layer providing step further includes the steps of: 
 annealing the ferromagnetic element.    
     
     
         34 . A method for providing a magnetic element comprising: 
 (a) providing a first pinned layer having a first pinned layer magnetization;    (b) providing a magnetic current confined layer having at least one channel in an insulating matrix, the at least one channel being ferromagnetic, and conductive, the at least one channel having at least one size that is sufficiently small that charge carriers can give rise to ballistic magnetoresistance in the at least one current confined layer; and    (c) providing a first free layer having a free layer magnetization, the magnetic current confined layer residing between the pinned layer and the free layer, the at least one channel extending through the insulating matrix between the pinned layer and the first free layer;    (d) providing a second free layer, the second free layer having a second free layer magnetization, the second free layer being magnetostatically coupled to the free layer;    (e) providing a second pinned layer being ferromagnetic and having a second pinned layer magnetization;    (f) providing a nonmagnetic spacer layer residing between the second free layer and the second pinned layer;    wherein the second free layer is configured to be written using spin transfer.    
     
     
         35 . The method of  claim 34  further comprising: 
 (g) providing a conductive separation layer residing between the first free layer and the second free layer, the conductive spacer layer for ensuring that the first free layer and the second free layer are magnetostatically coupled.    
     
     
         36 . The method of  claim 34  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) co-sputtering at least one ferromagnetic conductive material with at least one insulating matrix material, the at least one conducting channel being formed from the at least one ferromagnetic conductive material and the insulating matrix being formed from the at least one insulating matrix material.    
     
     
         37 . The method of  claim 34  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) forming the magnetic current confined layer using dry self-assembly.    
     
     
         38 . The method of  claim 34  wherein the magnetic current confined layer providing step (b) further includes the steps of: 
 (b1) providing at least one ferromagnetic conducting layer;    (b2) providing at least one insulating layer, the at least one insulating layer alternating with the at least one ferromagnetic conducting layer; and    (b3) providing a second magnetic conducting layer such that each of the at least one insulating layer is sandwiched between a magnetic conducting layer of the at least one magnetic conducting layer and/or the second magnetic conducting layer;    the at least one conducting channel being formed from the at least one magnetic conducting layer and the second magnetic conducting layer and the insulating matrix being formed from the at least one insulating layer.    
     
     
         39 . The method of  claim 34  wherein the current confined layer providing step further includes the steps of: 
 (b4) annealing the magnetic element.

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