Giant Cross-Plane Seebeck Effect in Oxide Metal Semiconductor Superlattices for Spin-Magnetic Thermoelectric Devices

Abstract

Lanthanum strontium manganate (La0.67Sro0.33MnO3, i.e., LSMO)/lanthanum manganate (LaMnO3, i.e., LMO) perovskite oxide metal/semiconductor superlattices were investigated for potential p-type thermoelectric applications. Growth optimizations were performed using pulsed laser deposition to achieve epitaxial superlattices of LSMO (metal)/LMO (p-type semiconductor) on strontium titanate (STO) substrates. The cross-plane Seebeck coefficient of the thermoelectric superlattice measured between the substrate and the capping layer has a value of at least 1600 μV/K measured at about 300K.

1 . A thermoelectric superlattice, comprising:
 a substrate;   a buffer layer disposed on the substrate;   at least one set of alternating layers of perovskites oxide La X SryMnO 3  (LSMO) and LaMnO 3  (LMO) disposed on the buffer layer; and   a capping layer disposed on the at least one set of LSMO and LMO,   the cross-plane Seebeck coefficient of the thermoelectric superlattice measured between the substrate and the capping layer having a value of at least 1600 μV/K measured at about 300° K.   
     
     
         2 . The thermoelectric superlattice of  claim 1 , the substrate is one of strontium titanate (STO), (La,Sr)(Al,Ta)O 3  (LSAT) and lanthanum aluminate (LaAIO 3 ). 
     
     
         3 . The thermoelectric superlattice of  claim 1 , the substrate has a lattice mismatch with the at least one set of LSMO and LMO of less than 5%. 
     
     
         4 . The thermoelectric superlattice of  claim 1 , the substrate has a lattice mismatch with the at least one set of LSMO and LMO of less than 2%. 
     
     
         5 . The thermoelectric superlattice of  claim 1 , the substrate has a lattice mismatch with the at least one set of LSMO and LMO of less than 1%. 
     
     
         6 . The thermoelectric superlattice of  claim 1 , the buffer layer having a thickness of between 50 nm to 500 nm. 
     
     
         7 . The thermoelectric superlattice of  claim 1 , the thickness of each layer of the at least one set of LMSO and LMO is between 2 nm to 21 nm. 
     
     
         8 . The thermoelectric superlattice of  claim 1 , the cross-plane Seebeck coefficient having a value of at least 2560 μV/K. 
     
     
         9 . The thermoelectric superlattice of  claim 1 , the capping layer is between about 50 nm and 200 nm. 
     
     
         10 . The thermoelectric superlattice of  claim 1 , the cross-plane electrical conductivity measured between the substrate and the capping layer is at least 6.3×10−3 ohm −1 ·cm −1  measured at about 300° K and the cross-plane thermal conductivity measured between the substrate and the capping layer is between 0.5 and 1.5 W/(m·K) at about 300° K.