Publications (7)39.97 Total impact
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Article: Link between spin fluctuations and electron pairing in copper oxide superconductors.
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ABSTRACT: Although it is generally accepted that superconductivity is unconventional in the high-transition-temperature copper oxides, the relative importance of phenomena such as spin and charge (stripe) order, superconductivity fluctuations, proximity to a Mott insulator, a pseudogap phase and quantum criticality are still a matter of debate. In electron-doped copper oxides, the absence of an anomalous pseudogap phase in the underdoped region of the phase diagram and weaker electron correlations suggest that Mott physics and other unidentified competing orders are less relevant and that antiferromagnetic spin fluctuations are the dominant feature. Here we report a study of magnetotransport in thin films of the electron-doped copper oxide La(2 - x)Ce(x)CuO(4). We show that a scattering rate that is linearly dependent on temperature--a key feature of the anomalous normal state properties of the copper oxides--is correlated with the electron pairing. We also show that an envelope of such scattering surrounds the superconducting phase, surviving to zero temperature when superconductivity is suppressed by magnetic fields. Comparison with similar behaviour found in organic superconductors strongly suggests that the linear dependence on temperature of the resistivity in the electron-doped copper oxides is caused by spin-fluctuation scattering.Nature 08/2011; 476(7358):73-5. · 36.28 Impact Factor -
Article: Link between spin fluctuations and Cooper pairing in copper oxide superconductors
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ABSTRACT: Although it is generally accepted that superconductivity (SC) is unconventional in the high- transition temperature copper oxides (high-Tc cuprates), the relative importance of phenomena such as spin and charge (stripe) order, SC fluctuations, proximity to a Mott insulator, a pseudogap phase, and quantum criticality are still a matter of great debate1. In electron-doped cuprates, the absence of an anomalous pseudogap phase in the underdoped region of the phase diagram2 and weaker electron correlations3,4, suggest that Mott physics and other unidentified competing orders are less relevant and that antiferromagnetic (AFM) spin fluctuations are the dominant feature. Here we demonstrate that a linear-temperature (T-linear) scattering rate - a key feature of the anomalous normal state properties of the cuprates - is correlated with the Cooper pairing (SC). Through a study of magnetotransport in thin films of the electron-doped cuprate La2 xCexCuO4 (LCCO), we show that an envelope of T-linear scattering surrounds the SC phase, and survives to zero temperature when superconductivity is suppressed by magnetic fields. Comparison with similar behavior found in organic superconductors5 strongly suggests that the T-linear resistivity is caused by spin-fluctuation scattering. Our results establish a fundamental connection between AFM spin fluctuations and the pairing mechanism of high temperature superconductivity in the cuprates.08/2011; -
Article: Anomalous Enhancement of the Superconducting Transition Temperature in Electron-doped La2-xCexCuO4 and Pr2-xCexCuO4 Cuprate Heterostructures
Physical Review B 02/2011; · 3.69 Impact Factor -
Article: Anomalous Enhancement of the Superconducting Transition Temperature in Electron-Doped Cuprate Heterostructures
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ABSTRACT: The superconducting transition temperature $T_{c}$ of multilayers of electron-doped cuprates, composed of underdoped (or undoped) and overdoped La% $_{2-x}$Ce$_{x}$CuO$_{4}$ (LCCO) and Pr$_{2-x}$Ce$_{x}$CuO$_{4}$ (PCCO) thin films, is found to increase significantly with respect to the $T_{c}$ of the corresponding single-phase films. By investigating the critical current density of superlattices with different doping levels and layer thicknesses, we find that the $T_{c}$ enhancement is caused by a redistribution of charge over an anomalously large distance.02/2011; -
Article: Evidence for Antiferromagnetic Order in La$_{2-x}$Ce$_{x}$CuO$_{4}$ from Angular Magnetoresistance Measurements
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ABSTRACT: We investigated the in-plane angular magnetoresistivity (AMR) of $% T^{^{\prime}}$-phase La$_{2-x}$Ce$_{x}$CuO$_{4}$ (LCCO) thin films ($% x=0.06-0.15$) fabricated by a pulsed laser deposition technique. The in-plane AMR with $\mathbf{H}\parallel ab$ shows a twofold symmetry instead of the fourfold behavior found in other electron-doped cuprates such as Pr$% _{2-x}$Ce$_{x}$CuO$_{4}$ and Nd$_{2-x}$Ce$_{x}$CuO$_{4}$. The twofold AMR disappears above a certain temperature, $T_{D}$. The $T_{D}(x)$ is well above $T_{c}(x)$ for $x=0.06$ ($\sim 110$ K), and decreases with increasing doping, until it is no longer observed above $T_{c}(x)$ at $x=0.15$. This twofold AMR below $T_{D}(x)$ is suggested to originate from an antiferromagnetic or spin density wave order. Comment: to be published in Phys. Rev. B, Vol. 80 (2009)06/2009; -
Article: Evidence for antiferromagnetic order in La_ {2− x} Ce_ {x} CuO_ {4} from angular magnetoresistance measurements
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ABSTRACT: We investigated the in-plane angular magnetoresistance (AMR) of T′-phase La2−xCexCuO4 thin films (x=0.06–0.15) fabricated by a pulsed laser deposition technique. The in-plane AMR with H∥ab shows a twofold symmetry instead of the fourfold behavior found in other electron-doped cuprates such as Pr2−xCexCuO4 and Nd2−xCexCuO4. The twofold AMR disappears above a certain temperature, TD. The TD(x) is well above Tc(x) for x=0.06 (∼110 K), and decreases with increasing doping until it is no longer observed above Tc(x) at x=0.15. This twofold AMR below TD(x) is suggested to originate from an antiferromagnetic or spin-density-wave order.Phys. Rev. B. 80(1). -
Article: Anomalous enhancement of the superconducting transition temperature of electron-doped La_ {2-x} Ce_ {x} CuO_ {4} and Pr_ {2-x} Ce_ {x} CuO_ {4} cuprate …
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ABSTRACT: The superconducting transition temperature Tc of multilayers of electron-doped cuprates, composed of underdoped (or undoped) and overdoped La2-xCexCuO4 (LCCO) and Pr2-xCexCuO4 (PCCO) thin films, is found to increase significantly with respect to the Tc of the corresponding single-phase films. By investigating the critical current density of superlattices with different doping levels and layer thicknesses, we find that the Tc enhancement is caused by a redistribution of charge over an anomalously large distance.Phys. Rev. B. 83(6).
Top co-authors
Top Journals
- Physical Review B (1)
- Nature (1)
Institutions
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2011
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University of Maryland, College Park
- Department of Physics
College Park, MD, USA
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