Abstract
Interaction between electrons has long been a focused topic in condensedmatter physics since it has led to the discoveries of astonishing phenomena, for example, highT_{c} superconductivity and colossal magnetoresistance (CMR) in stronglycorrelated materials. In the study of stronglycorrelated perovskite oxides, Nbdoped SrTiO_{3} (Nb:SrTiO_{3}) has been a workhorse not only as a conducting substrate, but also as a host possessing high carrier mobility. In this work, we report the observations of large linear magnetoresistance (LMR) and the metaltoinsulator transition (MIT) induced by magnetic field in heavilydoped Nb:STO (SrNb_{0.2}Ti_{0.8}O_{3}) epitaxial thin films. These phenomena are associated with the interplay between the large classical MR due to high carrier mobility and the electronic localization effect due to strong spinorbit coupling, implying that heavily Nbdoped Sr(Nb_{0.2}Ti_{0.8})O_{3} is promising for the application in spintronic devices.
Introduction
Recent discoveries of a high mobility (μ) twodimensional electron gas (2DEG), superconductivity, and ferromagnetism at the interface of SrTiO_{3} (STO) with other oxides such as LaAlO_{3} and LaTiO_{3}^{1,2,3,4}, have attracted interest in the properties of STO and doped STO. Conducting Nbdoped STO has also been studied as a potential candidate for creating a highμ 2DEG by using a δdoped quantum well structure^{5}. Previous studies have been conducted in a limited range of Nb concentration (0 ~ 5 at.%)^{6,7,8,9,10,11}, where μ was observed to be ~22,000 cm^{2}/Vs at 4 K for Nb concentrations of 0.02 at. % and decrease with increasing Nb concentration. In the heavy doping regime above 5 at. %, however, μ barely changes as a function of the Nb concentration contrary to the result of the low Nb concentration^{11}. On the other hand, heavily Nbdoped STO (20 at. % Nb) has been reported to show intriguing properties such as large thermoelectric power^{12}. Therefore, a deeper exploration into the effect of highconcentration doping on the carrier transport is needed to understand the physical properties of Nbdoped STO. In this work, we have investigated the magnetotransport properties of a heavily Nbdoped (~20 at.%) STO (Nb:STO) epitaxial thin film and observed intriguing phenomena, large linear magnetoresistance (LMR) and metaltoinsulator transition (MIT) induced by the magnetic field, which are unprecedented in Nb:STO with low Nb concentration. We also present a few evidences supporting that those phenomena are associated with the interplay between the large classical MR due to high carrier mobility and the localization effect due to strong spinorbit coupling.
Sr(Nb_{0.2}Ti_{0.8})O_{3} thin films are grown on STO (001) substrates by pulsed laser deposition (PLD). The Sr(Nb_{0.2}Ti_{0.8})O_{3} polycrystalline target with 20 at.% Nb is prepared by a conventional solidstate reaction technique. During the film growth, the laser power, the laser repetition rate, the substrate temperature, and the oxygen partial pressure are 1.6 J/cm^{2}, 2 Hz, 700 °C, and 1 × 10^{−5 }Torr, respectively. The composition of the grown film is found to be Sr:Ti:Nb = 1:0.79:0.21 using the Rutherford back scattering (RBS) method. We have examined the homogeneity of a film using the scanning electron microscopy with energy dispersive Xray spectroscopy (SEM/EDX, Supplemental Material S1). For the measurement of electrical properties, platinum is deposited by ebeam evaporation through a shadow mask to form the electrode pattern shown in Fig. 1(b). The longitudinal resistance (R_{xx} = V_{23}/I_{14}) and Hall resistance (R_{xy} = V_{65}/I_{14}) are measured with the excitation current of 100 μA using a SourceMeasure Unit (Keithley 2612A) and a nanovoltmeter (Keithley 2182). With this setup, the contacts are confirmed to be Ohmic by measuring the two probe resistance (V_{14}/I_{14}). The electrical properties have been investigated as a function of temperature (T) (1.8 K ~ 300 K) and magnetic field (B) to 9 T using a commercial cryogenfree cryostat (CMag Vari9, Cryomagnetics Inc.).
Figure 1(a) shows the Xray diffraction θ–2θ scan of a 65 nmthick Sr(Nb_{0.2}Ti_{0.8})O_{3} film near (002) peak of SrTiO_{3}, which indicates that the Sr(Nb_{0.2}Ti_{0.8})O_{3} films are epitaxial with the caxis along the surface normal direction without any features of secondary phases or phase segregations. The observed fringe pattern indicates the atomically smooth surface of our samples. From the fringe pattern, the thickness of the film is estimated to be about 65 nm consistent with the nominal thickness. The rocking curve of the (002) peak of a Sr(Nb_{0.2}Ti_{0.8})O_{3} film with the full width at half maximum (FWHM) of 0.046° indicates good crystallinity, as shown in the inset.
Figure 1(b) shows the basic transport properties of a 65 nmthick Sr(Nb_{0.2}Ti_{0.8})O_{3} film as a function of T, where the carrier density (n) is obtained by Hall measurement with B of ±2 T. The data displays a few intriguing features which have not been observed in lightly doped Nb:STO. First, note that, despite a huge n (~10^{21 }cm^{−3}), μ is unexpectedly high at low temperature (~14,000 cm^{2}/Vs at 1.8 K) resulting in a remarkably low resistivity (ρ) of about 8 × 10^{−8} Ωcm at 1.8 K. It is a quite unexpected observation since μ was reported to be 419 cm^{2}/Vs and 316 cm^{2}/Vs for Sr(Nb_{0.01}Ti_{0.99})O_{3} and Sr(Nb_{0.02}Ti_{0.98})O_{3}, respectively^{11}. Therefore, the observed high μ implies that there is a change in the transport mechanism or in the electronic band structure of the heavilydoped Nb:STO films. Below 100 K, the dependence of μ on T fits quite well to the Fermi liquid theory, 1/μ(T) = α + βT^{2}ln(1/T) where α and β are constants^{13} meaning that Sr(Nb_{0.2}Ti_{0.8})O_{3} films are degenerate. The deviation from the fit above 100 K could originate from the contribution of phonon scattering at high temperature^{14}. Or, it might be associated with the phase transition of STO from the tetragonal to the cubic phase above 105 K^{15,16}. This fact might lead to the emergence of multiple electronic bands. Indeed, as will be discussed in the later part, a fingerprint of the existence of multiple types of carriers is shown in the Bdependence of the Hall resistance (R_{xy}), unveiling one type of carrier having remarkably high μ at low temperature. Therefore, we believe that such a high μ originates from the change in the electronic band structure without ruling out other possibilities, for example, the effect of strain.
Another intriguing feature is shown in the nonmonotonic Tdependence of n. While n decreases with lowering T down to 100 K due to the reduction of thermal energy, it shows the opposite behavior below 100 K. This increase in n is associated with the increased dielectric screening due to the drastic increase of the dielectric permittivity of STO. In fact, a similar increase of n has been reported in oxygen vacancy (VO)doped STO^{17}.
In Fig. 2(a), the magnetoresistance (MR = R(B)/R(0)) a 65 nmthick is plotted as a function of B at 1.8 K for two different orientations of B. Note that both MR vs. B curves are quite linear irrespective of the orientation although the amplitude of MR is about threetimes higher for the case of the perpendicular B. In this work, we have investigated three samples with varying thickness (65 ~ 88 nm) and all investigated samples are shown to reproduce the LMR (Supplemental Material S2). As T increases, the linear dependence of MR turns into the classical quadratic dependence as shown in Fig. 2(b).
Since the first report of LMR in Bi crystals^{18}, LMR have attracted much interest because MR is expected to be an even function of B owing to symmetry. Nevertheless, LMR has been reported for various materials leading to the development of several theoretical models (for a review, see refs 19,20 and references therein). Recently, the interest has been revived due to the observation of LMR in topological insulators^{21,22}, multilayer epitaxial graphene^{23}, and Dirac semimetals such as Cd_{3}As_{2}^{24,25}. I. M. Lifshitz and V. G. Peschanskii explained the LMR using the classical electron trajectories in B when the material has an open Fermi surface^{26}. For materials with a closed Fermi surface, A. A. Abrikosov has developed a quantum mechanical picture for the LMR^{27}. According to his picture, in the quantum limit where the Landau level spacing is much larger than the thermal energy (, where , ω_{c}, and k_{B} are reduced Planck constant (h/2π), cyclotron frequency, and Boltzmann constant, respectively), only the lowest Landau level is occupied by electrons leading to the LMR. This LMR is dubbed as “quantum LMR (QLMR)”. About 30 years later, the LMR was observed in Ag_{2+δ}Te and Ag_{2+δ}Se under a low B down to 10 Oe and high T up to 300 K, which does not satisfy the quantum limit criterion^{28}. Again, based on his QLMR picture, A. A. Abrikosov also showed that the LMR could be observed at high T with low B under assumptions of (1) a gapless semiconductor with a linear energy vs. momentum (E vs. k) relation and (2) inhomogeneous carrier distribution^{19,29}. As an alternative explanation, M. M. Parish and P. B. Littlewood also showed that the LMR could appear in inhomogeneous materials making the Hall effect involved in the calculation of the longitudinal resistance^{30,31}.
In order to clarify the origin of the LMR in our samples, Tdependence of ρ and R_{xy} are investigated with varying B. Figure 3(a) shows ρ vs. T curves at various B. Note that, under a sufficiently strong B, ρ(T) shows a metalinsulator transition (MIT) at a certain temperature which increases with B (Fig. 3(b)). The insulating nature under a strong B at low T is also verified by the nonlinear current (I)voltage (V) characteristics at 2 K (Fig. 3(c)) in comparison with the linear IV curves at 10 K with varying B (Fig. 3(d)). In addition, we have found that, below the MIT temperature, the temperature dependence of the resistivity can be described by as shown in Fig. 3(e), implying that the carrier transport is dominated by the variablerange hopping (VRH)^{32}. It means that the carriers become localized by the magnetic field, invoking the effect of the weak antilocalization (WAL)^{33,34,35,36}.
In the three dimensional WAL, MR can be described by FukuyamaHoshino (FH) model^{37,38,39} which is expressed as the following equation (Eq. (1)).
where
In Eq. (1), B_{i}, B_{S}, and B_{SO} are the characteristic field for inelastic, spinflip, and spinorbit scattering, respectively. B_{ϕ} is the characteristic dephasing field given by B_{i} + 2B_{S}. Assuming that the measured MR is given by a sum of Δρ_{WAL} and the classical MR (Δρ_{orb} ~ B^{2}) due to Lorentz effect^{38}, we have fitted the observed MR as shown in Fig. 3(f). Note that the model well describes the observed LMR resulting in an estimation of the fitting parameters, B_{ϕ} = 0.112 T and B_{SO} = 5.618 T. These values are consistent with the result previously obtained in the LaAlO_{3}/SrTiO_{3} heterojunction in a high carrier density regime induced by the electric field effect^{40}, supporting the assumed model (Δρ = Δρ_{WAL} + Δρ_{orb.}) as the origin of the observed LMR.
As another check of the localization by the magnetic field, we have investigated R_{xy} as a function of B at various temperatures (Fig. 4(a)). Note that the curve is nonlinear at high temperatures (10 K ~ 50 K) in contrast to the linear dependence at low temperatures (below 10 K). The nonlinear R_{xy} vs. B curve indicates the existence of multiple electron bands. By using the twoband model for ρ and R_{xy}^{41}, we calculate n and μ of the two bands, (n_{1}, μ_{1}) and (n_{2}, μ_{2}), which are plotted in Fig. 4(b,c), respectively. The curve at 2 K is nearly linear resulting in erroneous values of n_{2} and μ_{2}, which are reflected by big error bars. Nevertheless, it is apparent that n_{2} consistently decreases resulting in ~10^{3}fold reduction with lowering T from 50 K to 2 K. On the other hand, n_{1} increases by about one order with lowering T, leading to an overall reduction of the carrier density (n = n_{1} + n_{2}). Furthermore, we have investigated the Tdependence of n under high magnetic field (±5 T) as shown in Fig. 4(d). Below 20 K, a drastic reduction of n(T)_{5T} is observed in contrast to the continued increase of n(T)_{2T}, which provides a clear evidence of the carrier localization induced by the magnetic field.
The resurgence of n(T)_{5T} below 10 K is also intriguing, which might imply that another mechanism or new phase sets in at low temperatures under strong Bfield. We have also investigated the magnetic properties to find a drastic increase in the magnetization (M) below 10 K and a little magnetic hysteresis at 5 K (see Supplemental Material S3). It seems to imply that the observed resurgence of n(T)_{5T} below 10 K is associated with a possible emergence of an unprecedented electronic and magnetic phase in the heavilydoped Nb:STO films.
The above results, that are, (1) VRHdominated transport under strong magnetic field, (2) the MR described by the FH model for the WAL, and (3) decrease in n under strong magnetic field, seem to indicate that the large LMR observed in Sr(Nb_{0.2}Ti_{0.8})O_{3} results from the interplay between a large classical MR due to the high carrier mobility and the localization effect due to strong spinorbit coupling. As other possibilities, the role of inhomogeneity suggested by M. M. Parish and P. B. Littlewood^{29,30} is ruled out based on the observation of homogeneous distribution of components as confirmed by the SEM/EDX (see Supplemental Material S1). On the other hand, an interpretation in terms of the QLMR model is not ruled out supposing that Sr(Nb_{0.2}Ti_{0.8})O_{3} should be a gapless material with a linear energymomentum relation and have inhomogeneous carrier distribution. According to the QLMR model, the normalized MR, , is known to approach to a constant value, which depends on the material, in the quantum limit and does not depend on T^{33}. It has been tested and found to be true in our case up to 10 K (Figure S4 in the Supplemental Material). Therefore, we cannot rule out the QLMR although there are many evidences supporting the interplay between the classical MR and the WAL as the origin for the observed large LMR in heavilydoped Sr(Nb_{0.2}Ti_{0.8})O_{3}.
To summarize, we have observed the nonsaturating LMR at low temperatures (below 20 K) and MIT induced by magnetic field in heavilydoped Sr(Nb_{0.2}Ti_{0.8})O_{3} epitaxial thin films grown on SrTiO_{3}. In addition, this material is featured by very low electrical resistivity (~8 × 10^{−8} Ωcm at 1.8 K) and high carrier mobility (~14,000 cm^{2}/Vs at 1.8 K), far exceeding an expectation obtained by an extrapolation from low Nb concentration regime. We propose that the LMR is associated with the interplay between the large classical MR due to high carrier mobility and the localization effect due to strong spinorbit coupling. Conversely, it means that the investigated Sr(Nb_{0.2}Ti_{0.8})O_{3} thin film possesses the high carrier mobility and the strong spinorbit coupling simultaneously, which imply a long spin diffusion length and an ability to effectively modulate electron’s spin, respectively. Therefore, we believe that Sr(Nb_{0.2}Ti_{0.8})O_{3} is a promising channel material for the application in spintronic devices although further exploration is needed into the heavily doped Nb:STO. A study on the dependence on the Nb concentration is ongoing, which will be presented in near future.
Additional Information
How to cite this article: Jin, H. et al. Large linear magnetoresistance in heavilydoped Nb:SrTiO_{3} epitaxial thin films. Sci. Rep. 6, 34295; doi: 10.1038/srep34295 (2016).
References
 1.
Brinkman, A. et al. Magnetic effects at the interface between nonmagnetic oxides. Nat Mater 6, 493–496, doi: http://www.nature.com/nmat/journal/v6/n7/suppinfo/nmat1931_S1.html (2007).
 2.
Ohtomo, A. & Hwang, H. Y. A highmobility electron gas at the LaAlO_{3}/SrTiO_{3} heterointerface. Nature 427, 423–426 (2004).
 3.
Reyren, N. et al. Superconducting Interfaces Between Insulating Oxides. Science 317, 1196–1199, 10.1126/science.1146006 (2007).
 4.
Ohtomo, A., Muller, D. A., Grazul, J. L. & Hwang, H. Y. Artificial chargemodulationin atomicscale perovskite titanate superlattices. Nature 419, 378–380 (2002).
 5.
Jalan, B., Stemmer, S., Mack, S. & Allen, S. J. Twodimensional electron gas in δdoped SrTiO_{3}. Physical Review B 82, 081103 (2010).
 6.
Frederikse, H. P. R. & Hosler, W. R. Hall Mobility in SrTiO_{3}. Physical Review 161, 822–827 (1967).
 7.
Liu, Z. Q. et al. Reversible roomtemperature ferromagnetism in Nbdoped SrTiO_{3} single crystals. Physical Review B 87, 220405 (2013).
 8.
Markovich, M. et al. Epitaxial growth of Nbdoped SrTiO_{3} films by pulsed laser deposition. Applied Surface Science 258, 9496–9500, doi: http://dx.doi.org/10.1016/j.apsusc.2012.02.041 (2012).
 9.
Takahashi, K. S. et al. Electrostatic modulation of the electronic properties of Nbdoped SrTiO_{3} superconducting films. Applied Physics Letters 84, 1722–1724, doi: http://dx.doi.org/10.1063/1.1667279 (2004).
 10.
Zhao, T. et al. Highly conductive Nb doped SrTiO_{3} epitaxial thin films grown by laser molecular beam epitaxy. Journal of Crystal Growth 212, 451–455, doi: http://dx.doi.org/10.1016/S00220248(00)003079 (2000).
 11.
Spinelli, A., Torija, M. A., Liu, C., Jan, C. & Leighton, C. Electronic transport in doped SrTiO_{3}: Conduction mechanisms and potential applications. Physical Review B 81, 155110 (2010).
 12.
Ohta, S. et al. Large thermoelectric performance of heavily Nbdoped SrTiO_{3} epitaxial film at high temperature. Applied Physics Letters 87, 092108, doi: http://dx.doi.org/10.1063/1.2035889 (2005).
 13.
Gould, H. & Ma, S.k. LowTemperature Mobility of Heavy Impurities in Fermi Liquids. Physical Review Letters 21, 1379–1382 (1968).
 14.
Schoofs, F., Egilmez, M., Fix, T., MacManusDriscoll, J. L. & Blamire, M. G. Impact of structural transitions on electron transport at LaAlO_{3}/SrTiO_{3} heterointerfaces. Applied Physics Letters 100, 081601, doi: http://dx.doi.org/10.1063/1.3687706 (2012).
 15.
Lytle, F. W. X‐Ray Diffractometry of Low‐Temperature Phase Transformations in Strontium Titanate. Journal of Applied Physics 35, 2212–2215, doi: http://dx.doi.org/10.1063/1.1702820 (1964).
 16.
Rimai, L. & deMars, G. A. Electron Paramagnetic Resonance of Trivalent Gadolinium Ions in Strontium and Barium Titanates. Physical Review 127, 702–710 (1962).
 17.
Liu, Z. Q. et al. Magneticfield induced resistivity minimum with inplane linear magnetoresistance of the Fermi liquid in SrTiO_{3} single crystals. Physical Review B 85, 155114 (2012).
 18.
Kapitza, P. The Study of the Specific Resistance of Bismuth Crystals and Its Change in Strong Magnetic Fields and Some Allied Problems. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 119, 358–443, 10.1098/rspa.1928.0103 (1928).
 19.
Abrikosov, A. A. Quantum linear magnetoresistance. EPL (Europhysics Letters) 49, 789 (2000).
 20.
Hu, J. & Rosenbaum, T. F. Classical and quantum routes to linear magnetoresistance. Nat Mater 7, 697–700 (2008).
 21.
Wang, X., Du, Y., Dou, S. & Zhang, C. Room Temperature Giant and Linear Magnetoresistance in Topological Insulator Bi_{2}Te_{3} Nanosheets. Physical Review Letters 108, 266806 (2012).
 22.
Wang, W. et al. Large Linear Magnetoresistance and Shubnikovde Hass Oscillations in Single Crystals of YPdBi Heusler Topological Insulators. Scientific reports 3, 2181, 10.1038/srep02181 http://www.nature.com/articles/srep02181#supplementaryinformation (2013).
 23.
Friedman, A. L. et al. Quantum Linear Magnetoresistance in Multilayer Epitaxial Graphene. Nano Letters 10, 3962–3965, 10.1021/nl101797d (2010).
 24.
Novak, M., Sasaki, S., Segawa, K. & Ando, Y. Large linear magnetoresistance in the Dirac semimetal TlBiSSe. Physical Review B 91, 041203 (2015).
 25.
He, L. P. et al. Quantum Transport Evidence for the ThreeDimensional Dirac Semimetal Phase in Cd_{3}As_{2}. Physical Review Letters 113, 246402 (2014).
 26.
Lifshitz, I. M. & Peschanskii, V. G. Galvanomagnetic Characteristics of Metals with Open Fermi Surfaces. Sov. Phys. JETP 8, 875–883 (1959).
 27.
Abrikosov, A. A. Gal Vanomagnetic Phenomena In Metals In The Quantum Limit. Sov. Phys. JETP 29, 746–753 (1969).
 28.
Xu, R. et al. Large magnetoresistance in nonmagnetic silver chalcogenides. Nature 390, 57–60 (1997).
 29.
Abrikosov, A. A. Quantum magnetoresistance. Physical Review B 58, 2788–2794 (1998).
 30.
Parish, M. M. & Littlewood, P. B. Nonsaturating magnetoresistance in heavily disordered semiconductors. Nature 426, 162–165 (2003).
 31.
Parish, M. M. & Littlewood, P. B. Classical magnetotransport of inhomogeneous conductors. Physical Review B 72, 094417 (2005).
 32.
Mott, N. F. Conduction in noncrystalline materials. Philosophical Magazine 19, 835–852, 10.1080/14786436908216338 (1969).
 33.
Qu, D.X., Hor, Y. S., Xiong, J., Cava, R. J. & Ong, N. P. Quantum Oscillations and Hall Anomaly of Surface States in the Topological Insulator Bi_{2}Te_{3}. Science 329, 821–824, 10.1126/science.1189792 (2010).
 34.
Xiong, J. et al. Quantum oscillations in a topological insulator Bi_{2}Te_{2}Se with large bulk resistivity (). Physica E: Lowdimensional Systems and Nanostructures 44, 917–920, doi: http://dx.doi.org/10.1016/j.physe.2011.09.011 (2012).
 35.
Checkelsky, J. G. et al. Quantum Interference in Macroscopic Crystals of Nonmetallic Bi_{2}Se_{3}. Physical Review Letters 103, 246601 (2009).
 36.
Altshuler, B. L., Aronov, A. G. & Khmelnitsky, D. E. Effects of electronelectron collisions with small energy transfers on quantum localisation. Journal of Physics C: Solid State Physics 15, 7367 (1982).
 37.
Fukuyama, H. & Hoshino, K. Effect of SpinOrbit Interaction on Magnetoresistance in the Weakly Localized Regime of ThreeDimensional Disordered Systems. Journal of the Physical Society of Japan 50, 2131–2132, 10.1143/JPSJ.50.2131 (1981).
 38.
Hu, J., Liu, J. Y. & Mao, Z. Q. Spin–orbit coupling and weak antilocalization in the thermoelectric material βK_{2}Bi_{8}Se_{13}. Journal of Physics: Condensed Matter 26, 095801 (2014).
 39.
Hikami, S., Larkin, A. I. & Nagaoka, Y. SpinOrbit Interaction and Magnetoresistance in the Two Dimensional Random System. Progress of Theoretical Physics 63, 707–710, 10.1143/ptp.63.707 (1980).
 40.
Caviglia, A. D. et al. Tunable Rashba SpinOrbit Interaction at Oxide Interfaces. Physical Review Letters 104, 126803 (2010).
 41.
Ashcroft, N. W. & Mermin, N. D. Solid state physics 240 (Holt, Rinehart and Winston, 1976).
Acknowledgements
The authors thank Dr. Satoshi Okamoto for discussions and valuable comments. This work was supported by the Korea Institute of Science and Technology (KIST) through 2E26420 and 2E26370. B.H.P. was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MSIP) (No. 2013R1A3A2042120). S.S.A.S. acknowledges the support of National Science Foundation grant DMR1454200 for sample synthesis.
Author information
Affiliations
Center for Electronic Materials, Korea Institute of Science and Technology, Seoul 136791, Korea
 Hyunwoo Jin
 , SeungHyub Baek
 , JinSang Kim
 , Byungki Cheong
 & Suyoun Lee
Institute of Physics and Applied Physics, Yonsei University, Seoul 120749, Korea
 Hyunwoo Jin
 & Changyoung Kim
Department of Physics and Astronomy, Institute of Applied Physics, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 151747, Korea
 Keundong Lee
Department of Nanomaterials Science and Technology, University of Science and Technology, Daejeon, 305333, Republic of Korea
 SeungHyub Baek
 & Suyoun Lee
Department of Physics, Konkuk University, Seoul 143701, Korea
 Bae Ho Park
Department of Physics, The Catholic University of Korea, Bucheon 420743, Korea
 Sungwon Yoon
 & B. J. Suh
Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506, USA
 S. S. A. Seo
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Contributions
H.J. and S.L. conceived the experiment, synthesized the sample by PLD, and performed electrical characterization. K.L., S.H.B., B.H.P., J.S.K. and S.S.A.S. contributed to the fabrication of heavilydoped Nb:STO thin films. B.k.C. and C.K. contributed to the measurement and analysis of magnetotransport properties. S.Y. and B.J.S. contributed to the measurement and analysis of the magnetic properties. H.J., S.S.A.S. and S.L. wrote the manuscript with discussions and improvements from all authors.
Competing interests
The authors declare no competing financial interests.
Corresponding author
Correspondence to Suyoun Lee.
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