Giant cross-plane seebeck effect in oxide metal semiconductor superlattices for spin-magnetic thermoelectric devices
Lanthanum strontium manganate (La 0.67 Sr 0.33 MnO 3 , i.e., LSMO)/lanthanum manganate (LaMnO 3 , 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 0.67 Sr 0.33 MnO 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 electrical conductivity of the thermoelectric superlattice measured between the substrate and the capping layer having a value of at least 8×10 −4 ohm −1 −cm −1 measured at about 300K; and
wherein each layer in the at least one set of alternating layers has a same thickness, and wherein said same thickness is 2-21 nm and wherein the thickness of the capping layer is 3-20 times said same thickness.
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 (LaAlO 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 cross-plane electrical conductivity of the thermoelectric superlattice having a value of at least 6.3×10 −3 1/(ohm·cm) measured at about 300K.
8. The thermoelectric superlattice of claim 1 , the capping layer is between about 50 nm and 200 nm.
9. The thermoelectric superlattice of claim 1 , the cross-plane Seebeck coefficient measured between the substrate and the capping layer is at least 1520 μV/K at about 300K 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 300K.