Dimensional crossover of polaron dynamics in Nb:SrTiO3/SrTiO3 superlattices: Possible mechanism of thermopower enhancement

被引：32

作者：

Choi, Woo Seok ^{[1
]}

Ohta, Hiromichi ^{[2
,3
]}

Moon, Soon Jae ^{[1
]}

Lee, Yun Sang ^{[4
]}

Noh, Tae Won ^{[1
]}

机构：

[1] Seoul Natl Univ, ReCFI, Dept Phys & Astron, Seoul 151747, South Korea

[2] Nagoya Univ, Grad Sch Engn, Nagoya, Aichi 4648603, Japan

[3] Japan Sci & Technol Agcy, PRESTO, Kawaguchi, Saitama 3320012, Japan

[4] Soongsil Univ, Dept Phys, Seoul 156743, South Korea

来源：

PHYSICAL REVIEW B | 2010年 / 82卷 / 02期

关键词：

THERMOELECTRIC-MATERIALS; SRTIO3;

D O I：

10.1103/PhysRevB.82.024301

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Using optical spectroscopy, we investigated the electrodynamic properties of Nb:SrTiO3/SrTiO3 superlattices. In these superlattices, a large enhancement of the Seebeck coefficient (S) has been reported with decreasing Nb:SrTiO3 layer thickness [H. Ohta et al., Nature Mater. 6, 129 (2007)]. By analyzing the optical spectra, we found that the polaron plays an important role in determining the electrodynamic properties of the superlattices. With decreasing Nb: SrTiO3 layer thickness from 11 to 1 unit cell, we observed a threefold enhancement of the polaron effective mass and relaxation time. Such increases were attributed to a dimensional crossover of the polaron from three-dimensional to quasi-two-dimensional. Moreover, the modified nature of the polaron at low dimensions enhanced the thermoelectric properties of the oxide superlattice, by simultaneously increasing S and preventing the decrease in carrier mobility. Our results indicate that strong electron-phonon coupling can provide an alternative pathway in searching for efficient thermoelectric materials.

引用

页数：5

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