On mobility of electrons in a shallow Fermi sea over a rough seafloor

Behnia, Kamran

doi:10.1088/0953-8984/27/37/375501

Cited by 30 publications

(39 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been argued [42] that these peculiar features of mobility in dilute metallic strontium titanate can be traced back to the long effective Bohr radius, a * B , of the parent insulator. The large electric permittivity [13] elongates the Bohr radius to 600 nm, which is to be compared to 1.5 nm in silicon.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Charge transport in a polar metal

et al. 2019

Self Cite

View full text Add to dashboard Cite

The fate of electric dipoles inside a Fermi sea is an old issue, yet poorly-explored. Sr1−xCaxTiO3 hosts a robust but dilute ferroelectricity in a narrow (0.002 < x < 0.02) window of substitution. This insulator becomes metallic by removal of a tiny fraction of its oxygen atoms. Here, we present a detailed study of low-temperature charge transport in Sr1−xCaxTiO 3−δ , documenting the evolution of resistivity with increasing carrier concentration (n). Below a threshold carrier concentration, n * (x), the polar structural phase transition has a clear signature in resistivity and Ca substitution significantly reduces the 2 K mobility at a given carrier density. For three different Ca concentrations, we find that the phase transition fades away when one mobile electron is introduced for about 7.9±0.6 dipoles. This threshold corresponds to the expected peak in anti-ferroelectric coupling mediated by a diplolar counterpart of Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Our results imply that the transition is driven by dipole-dipole interaction, even in presence of a dilute Fermi sea. At higher carrier concentrations, our data resolves slight upturns in low-temperature resistivity in both Ca-free and Ca-substituted samples, reminiscent of Kondo effect and most probably due to oxygen vacancies.arXiv:1909.04278v1 [cond-mat.supr-con]

show abstract

Section: Resultsmentioning

confidence: 99%

“…The combination of a large a * B and a small k F elongates the screening length and therefore short-distant irregularities in the dopant distribution are smoothed out. This simple approach yields this expression for mobility [42]:…”

Section: Resultsmentioning

confidence: 99%

Charge transport in a polar metal

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…As a consequence, quantum oscillations are easily detectable in moderate magnetic fields [34][35][36]. The large magnitude of defect-limited mobility at low temperature and its evolution with carrier concentration can be explained in a simple model [37] invoking the long effective Bohr radius of the quantum paraelectric [38] parent insulator.…”

Section: Resultsmentioning

confidence: 99%

Metallicity without quasi-particles in room-temperature strontium titanate

et al. 2017

Self Cite

View full text Add to dashboard Cite

Cooling oxygen-deficient strontium titanate to liquid-helium temperature leads to a decrease in its electrical resistivity by several orders of magnitude. The temperature dependence of resistivity follows a rough T 3 behavior before becoming T 2 in the lowtemperature limit, as expected in a Fermi liquid. Here, we show that the roughly cubic resistivity above 100 K corresponds to a regime where the quasi-particle mean-free-path is shorter than the electron wave-length and the interatomic distance. These criteria define the Mott-Ioffe-Regel limit. Exceeding this limit is the hallmark of strange metallicity, which occurs in strontium titanate well below room temperature, in contrast to other perovskytes. We argue that the T 3 -resistivity cannot be accounted for by electron-phonon scattering à la Bloch-Gruneisen and consider an alternative scheme based on Landauer transmission between individual dopants hosting large polarons. We find a scaling relationship between carrier mobility, the electric permittivity and the frequency of transverse optical soft mode in this temperature range. Providing an account of this observation emerges as a challenge to theory. npj Quantum Materials (2017)2:41 ; doi:10.1038/s41535-017-0044-5 INTRODUCTIONThe existence of well-defined quasi-particles is taken for granted in the Boltzmann-Drude picture of electronic transport. In this picture, carriers of charge or energy are scattered after traveling a finite distance. The Mott-Ioffe-Regel (MIR) limit is attained when the mean-free-path of a carrier falls below its Fermi wavelength or the interatomic distance.1 In most metals, resistivity saturates when this limit is approached. But in "bad" 2 or "strange" 3 metals, it continues to increase. 4 It is indeed strange when the mean-freepath persists to fall after attaining its shortest conceivable magnitude and often unexpected behavior is considered bad.In most cases, bad metals present a linear temperature dependence beyond the MIR limit. Bruin et al. 5 recently noticed that the T-linear scattering rate in numerous metals, either ordinary or strange, has a similar magnitude. This observation suggests the relevance of a universal Planck timescale (τ P $

show abstract

“…This protects the percolated Fermi sea even when its depth becomes more than three orders of magnitude smaller than the gap and keeps the mobility of the carriers high, because any local departure from lattice perfection is averaged over long distances. The doping dependence of mobility, which follows n −α with α close to unity, can be explained with a set of most unsophisticated assumptions, leading to an expression for the intrinsic mobility of a metallic semiconductor with a random distribution of dopants [33].…”

Section: Bohr Radius Metal-insulator Transition and High Mobilitymentioning

confidence: 99%

Metallicity and Superconductivity in Doped Strontium Titanate

Collignon

Lin

Rischau

et al. 2019

Annu. Rev. Condens. Matter Phys.

Self Cite

122

127

View full text Add to dashboard Cite

Strontium titanate is a wide-gap semiconductor avoiding a ferroelectric instability thanks to quantum fluctuations. This proximity leads to strong screening of static Coulomb interaction and paves the way for the emergence of a very dilute metal with extremely mobile carriers at liquid-helium temperature. Upon warming, mobility decreases by several orders of magnitude. Yet, metallicity persists above room temperature even when the apparent mean free path falls below the electron wavelength. The superconducting instability survives at exceptionally low concentrations and beyond the boundaries of MigdalEliashberg approximation. An intimate connection between dilute superconductivity and aborted ferroelectricity is widely suspected. In this review, we give a brief account of ongoing research on bulk strontium titanate as an insulator, a metal, and a superconductor. CONTENTS

show abstract

On mobility of electrons in a shallow Fermi sea over a rough seafloor

Cited by 30 publications

References 51 publications

Charge transport in a polar metal

Charge transport in a polar metal

Metallicity without quasi-particles in room-temperature strontium titanate

Metallicity and Superconductivity in Doped Strontium Titanate

Contact Info

Product

Resources

About