Electronic transport in thin films of ${\mathrm{BaPbO}}_{3}$: Unraveling two-dimensional quantum effects

Electronic transport in thin films of ${BaPbO}_{3}$ : Unraveling two-dimensional quantum effects

P. Seiler, R. Bartel, T. Kopp, and G. Hammerl

Phys. Rev. B 100, 165402 – Published 2 October 2019

Abstract

Recently, perovskite-related $BaPb O_{3}$ has attracted attention due to its hidden topological properties and, moreover, has been used as a thin layer in heterostructures to induce two-dimensional superconductivity. Here we investigate the normal-state electronic transport properties of thin films of $BaPb O_{3}$ . Temperature- and magnetic-field-dependent sheet resistances are strongly affected by two-dimensional quantum effects. Our analysis decodes the interplay of spin-orbit coupling, disorder, and electron-electron interaction in this compound. Like for recently discussed topological materials, we find that weak antilocalization is the dominant protagonist in magnetotransport, whereas electron-electron interactions play a pronounced role in the temperature dependence. A systematic understanding of these quantum effects is essential to allow for accurate control of properties not only of thin films of $BaPb O_{3}$ but also of topological heterostructures.

Received 23 July 2019

DOI:https://doi.org/10.1103/PhysRevB.100.165402

Physics Subject Headings (PhySH)

Magnetoresistance Magnetotransport Spin-orbit coupling Weak antilocalization

Heterostructures Interfaces Transition metal oxides Two-dimensional electron system

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

P. Seiler , R. Bartel, T. Kopp, and G. Hammerl ^*

Center for Electronic Correlations and Magnetism, Experimental Physics VI, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany

^*german.hammerl@physik.uni-augsburg.de

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Vol. 100, Iss. 16 — 15 October 2019

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Figure 1
Exemplary magnetoresistance (MR) data and fit parameters taken and retrieved from a 4.8-nm-thick $BaPb O_{3}$ thin film grown on a (001)-oriented $SrTi O_{3}$ substrate. (a) Temperature-dependent magnetoresistance as a function of an applied external magnetic field. The dotted lines are fits modeling the quantum corrections following Eq. (8). (b) Extracted spin-orbit fields $B_{so}$ (red) and inelastic fields $B_{i}$ (blue). At low temperatures $B_{so}$ is clearly larger than $B_{i}$ with maximum values reaching 0.24 T. At high temperatures $B_{i} ≫ B_{so}$ ; therefore, the fitted value of $B_{so}$ loses its significance (red circle). Gray lines are guides to the eye. (c) Temperature dependence of the inelastic magnetic field $B_{i}$ following Eq. (4).
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Figure 2
(a) Observed dependence of the sheet resistance $R_{S}$ on temperature. The progression can be understood in terms of electron-phonon scattering at high temperatures but is also dominated by dislocation scattering [48]. (b) The progression of the change in conductivity with respect to the reference temperature $T_{ref} = 25$ K on a logarithmic scale (blue data). Following the WAL analysis, a metallic ground state is expected (red line). Reevaluating the data by subtraction of the WAL contribution (red arrows) reveals a logarithmic progression (green dots labeled “data corr.”). The fit of this progression is in excellent agreement with weakly screened EEI.
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Figure 3
Progression of the negative conductivity correction over temperature $T$ and magnetic field $B$ following Eq. (12) with respect to the chosen reference temperature $T_{ref} = 25$ K and setting $B_{so} = 0.24$ T as extracted from the fits. The blue lines indicate where data are taken in magnetoresistance measurements. We extrapolate the magnetoconductivity to the case $B = 0$ (red line). This is the corresponding WAL quantum correction for zero magnetic field.
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Figure 4
Exemplary measurement of the Hall resistance $R_{H}$ as a function of the magnetic field of a $d_{BPO} = 4.6 nm$ thick $BaPb O_{3}$ thin film grown by pulsed laser deposition. The Hall resistance $R_{H}$ depends linearly on the wide applied magnetic field, strongly suggesting single-band behavior. The surface charge carrier density extracted from the linear fit (dashed line) calculates to $n_{el} = 1.5 \times 10^{12} {cm}^{- 2}$ at 1.8 K.
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Figure 5
Exemplary magnetoresistance (MR) data and fit parameter following Fig. 1, taken and retrieved from a 21.3-nm-thick $BaPb O_{3}$ thin film grown on a (001)-oriented $SrTi O_{3}$ substrate showing a maximum value of $B_{so} = 0.11$ T.
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Figure 6
(a) Exemplary observed dependence of the sheet resistance $R_{S}$ on temperature retrieved for a $d_{BPO} = 21.3 nm$ thick $BaPb O_{3}$ sample, following Fig. 2. (b) The analysis follows the procedure described in the main text with chosen reference temperature $T_{ref} = 12$ K and reveals almost completely unscreened EEI modeled by $ζ = 0.97$ .
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Physical Review B

covering condensed matter and materials physics

Electronic transport in thin films of ${BaPbO}_{3}$ : Unraveling two-dimensional quantum effects

P. Seiler, R. Bartel, T. Kopp, and G. Hammerl

Phys. Rev. B 100, 165402 – Published 2 October 2019

Abstract

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Physical Review B

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Electronic transport in thin films of BaPbO3: Unraveling two-dimensional quantum effects

P. Seiler, R. Bartel, T. Kopp, and G. Hammerl

Phys. Rev. B 100, 165402 – Published 2 October 2019

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Electronic transport in thin films of ${BaPbO}_{3}$ : Unraveling two-dimensional quantum effects