TY - JOUR

T1 - Enhanced Seebeck coefficient of quantum-confined electrons in SrTiO 3/SrTi0.8Nb0.2O3 superlattices

AU - Mune, Yoriko

AU - Ohta, Hiromichi

AU - Koumoto, Kunihito

AU - Mizoguchi, Teruyasu

AU - Ikuhara, Yuichi

N1 - Funding Information:
This work was financially supported by the Industrial Technology Research Grant Program in 2005 from the New Energy and Industrial Technology Development Organization (NEDO), and a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (No. 18686054).

PY - 2007

Y1 - 2007

N2 - We report two-dimensional Seebeck coefficients (∫S∫2D) of [(SrTi O3) x (Sr Ti0.8 Nb0.2 O3) y] 20 (x=1-60, y=1-20) superlattices, which were grown on the (100) face of insulating LaAl O3 substrates to clarify the origin of the giant ∫S∫2D values of the SrTi O3 superlattices [H. Ohta, Nat. Mater. 6, 129 (2007)]. The ∫S∫2D values of the [(SrTi O3) 17 (Sr Ti0.8 Nb0.2 O3) y] 20 superlattices increased proportionally to y-0.5 and reached 320 μV K-1 (y=1), which is approximately five times larger than that of the Sr Ti0.8 Nb0.2 O3 bulk (∫S∫3D =61 μV K-1). The slope of the log ∫S∫2D -log y plots was -0.5, proving that the density of states in the ground state for SrTi O3 increases inversely proportionally to y. The critical barrier thickness for quantum electron confinement was also clarified to be 6.25 nm (16 unit cells of SrTi O3).

AB - We report two-dimensional Seebeck coefficients (∫S∫2D) of [(SrTi O3) x (Sr Ti0.8 Nb0.2 O3) y] 20 (x=1-60, y=1-20) superlattices, which were grown on the (100) face of insulating LaAl O3 substrates to clarify the origin of the giant ∫S∫2D values of the SrTi O3 superlattices [H. Ohta, Nat. Mater. 6, 129 (2007)]. The ∫S∫2D values of the [(SrTi O3) 17 (Sr Ti0.8 Nb0.2 O3) y] 20 superlattices increased proportionally to y-0.5 and reached 320 μV K-1 (y=1), which is approximately five times larger than that of the Sr Ti0.8 Nb0.2 O3 bulk (∫S∫3D =61 μV K-1). The slope of the log ∫S∫2D -log y plots was -0.5, proving that the density of states in the ground state for SrTi O3 increases inversely proportionally to y. The critical barrier thickness for quantum electron confinement was also clarified to be 6.25 nm (16 unit cells of SrTi O3).

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U2 - 10.1063/1.2809364

DO - 10.1063/1.2809364

M3 - Article

AN - SCOPUS:36048958515

VL - 91

JO - Applied Physics Letters

JF - Applied Physics Letters

SN - 0003-6951

IS - 19

M1 - 192105

ER -