Spin valves using organic spacers and spin-organic light-emitting structures using ferromagnetic electrodes

Abstract

The spacer in a spin-valve is replaced with an organic layer, allowing for numerous applications, including light-emitting structures. The invention demonstrates that the spin coherence of the organic material is sufficiently long that the carriers do not lose their spin memory even in traversing a thicker passive barrier. At least three methods to fabricate the organic spin-valve devices are disclosed, in which the difficulties associated with depositing the ferromagnetic (FM) and organic layers are addressed.

1 . A spin-valve device, comprising: 
 two ferromagnetic electrodes; and    an organic spacer layer between the two ferromagnetic electrodes.    
     
     
         2 . The spin-valve device of  claim 1 , wherein the electrodes and spacer are vertically stacked.  
     
     
         3 . The spin-valve device of  claim 1 , including a metallic ferromagnetic electrode.  
     
     
         4 . The spin-valve device of  claim 3 , wherein the ferromagnetic electrode is composed of Co, Ni, Fe, or alloys thereof.  
     
     
         5 . The spin-valve device of  claim 1 , including a semi-metallic ferromagnetic electrode.  
     
     
         6 . The spin-valve device of  claim 5 , wherein the ferromagnetic electrode is ReMnO 3  or CrO 2 .  
     
     
         7 . The spin-valve device of  claim 1 , including a π-conjugated organic semiconductor ferromagnetic electrode.  
     
     
         8 . The spin-valve device of  claim 7 , wherein the ferromagnetic electrode is selected from polythiophenes, polyparaphenylenes, polyparaphenylenevynylenes, and polyfluorenes and their block co-polymers.  
     
     
         9 . The spin-valve device of  claim 7 , wherein the ferromagnetic electrode is 4-thiophene, 6-thiophen, or 3-PPV, such as distyryl benzene, or other small oligomer.  
     
     
         10 . The spin-valve device of  claim 7 , wherein the ferromagnetic electrode is a porphyrine, AlQ 3 , PBD, dendrimer, or other small molecule.  
     
     
         11 . The spin-valve device of  claim 1 , wherein the organic spacer layer has a thickness of 50 nanometers or greater.  
     
     
         12 . The spin-valve device of  claim 1 , wherein the thickness of one or both of the ferromagnetic electrodes is 100 nanometers or greater.  
     
     
         13 . The spin-valve device of  claim 1 , wherein the electrodes and spacer layer are configured in a planar geometry.  
     
     
         14 . The spin-valve device of  claim 1 , wherein the electrodes are of the same material but with different widths to control the magnetization switching in each electrode independently.  
     
     
         15 . The spin-valve device of  claim 1 , wherein the electrodes and spacer layer are configured to show an I-V response curve characteristic of a diode.  
     
     
         16 . The spin-valve device of  claim 1 , wherein one or both of the electrodes inject electrons and holes to generate an electroluminescence emission upon application of an externally applied bias voltage.