Low-temperature dependence of the thermomagnetic transport properties of the SrTiO${}_3$/LaAlO${}_3$ interface

Transport measurements are reported, including Hall, Seebeck, and Nernst effects. All of these transport properties exhibit anomalous field and temperature dependencies, with a change of behavior observed at $H\sim 1.5$ T and $T\sim 15$ K. The low-temperature, low-field behaviors of all transport properties were reconciled using a simple two-band analysis. A more detailed model is required in order to explain the high-magnetic-field regime.

Figure 1

(a) Electrical resistance as a function of temperature.  (b) Electrical resistance as a function of applied perpendicular magnetic field.

Figure 2

(a) ${\rho }_{xy}$ as a function of applied perpendicular magnetic field. (b) Fit of the ${\rho }_{xy}\left(H\right)$ measurements using a model of multiple types of charge carriers. The fit was done for the field range of $-6$ to 6 T.

Figure 3

Nernst signal of the SrTiO${}_3$-LaAlO${}_3$ sample. (a) Measurements for the temperature range of $15<T<40$ K. (b) Measurements for the temperature range of $2.2<T<15$ K.

Figure 4

Nernst signal and thermopower measurements of the SrTiO${}_3$-LaAlO${}_3$ sample. (a) Nernst signal as a function of temperature from 30 to 3 K. (b) Measurement of thermopower as a function of temperature from 30 to 3 K.

Figure 5

Calculated electrical properties of the 2DEG assuming a two-band model. (a) Electrical conduction contributed by each conductance band. (b) Hall coefficient of each conductance band.

Figure 6

(a) Density of charge carriers of each conductance band. (b) Linear part of the Nernst signal at low temperatures and low magnetic fields, used for the calculation of the Nernst coefficients $Q_i$.

Figure 7

Fit for thermopower and the Nernst coefficient. (a) Measured thermopower data (black), calculated fit (red), and values associated with each type of charge carrier (blue and green). (b) Measured Nernst data (black), calculated fit (red), and values associated with each type of charge carrier (blue and green).