Etienne Boaknin

Field-Induced Quantum Critical Point in C e C o I n 5

The resistivity of the heavy-fermion superconductor CeCoIn5 was measured as a function of temperature, down to 25 mK and in magnetic fields of up to 16 T applied perpendicular to the basal plane. With increasing field, we observe a suppression of the non-Fermi liquid behavior, rho approximately T, and the development of a Fermi liquid state, with its characteristic rho=rho(0)+AT2 dependence. The field dependence of the T2 coefficient shows critical behavior with an exponent of 1.37. This is evidence for a field-induced quantum critical point (QCP), occurring at a critical field which coincides, within experimental accuracy, with the superconducting critical field H(c2). We discuss the relation of this field-tuned QCP to a change in the magnetic state, seen as a change in magnetoresistance from positive to negative, at a crossover line that has a common border with the superconducting region below approximately 1 K.

Heat Transport in a Strongly Overdoped Cuprate: Fermi Liquid and a Pure d-Wave BCS Superconductor

The transport of heat and charge in the overdoped cuprate superconductor Tl(2)Ba2CuO(6+delta) was measured down to low temperature. In the normal state, obtained by applying a magnetic field greater than the upper critical field, the Wiedemann-Franz law is verified to hold perfectly. In the superconducting state, a large residual linear term is observed in the thermal conductivity, in quantitative agreement with BCS theory for a d-wave superconductor. This is compelling evidence that the electrons in overdoped cuprates form a Fermi liquid, with no indication of spin-charge separation.

Thermal conductivity across the phase diagram of cuprates: Low-energy quasiparticles and doping dependence of the superconducting gap

Heat transport in the cuprate superconductors

Heat conduction in the vortex state of NbSe2: evidence for multiband superconductivity.

{\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{y}

Field-induced quantum critical point in CeCoIn5

and

Highly Anisotropic Gap Function in Borocarbide Superconductor LuNi2B2C

{\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}

Unpaired electrons in the heavy-fermion superconductor CeCoIn5

was measured at low temperatures as a function of doping. A residual linear term

Field-induced thermal metal-to-insulator transition in underdoped LSCO

{\ensuremath{\kappa}}_{0}/T

Doping dependence of the superconducting gap in Tl 2 Ba 2 CuO 6 + δ from heat transport

is observed throughout the superconducting region and it decreases steadily as the Mott insulator is approached from the overdoped regime. The low-energy quasiparticle gap extracted from

Heat conduction in the borocarbide superconductor LuNi2B2C

{\ensuremath{\kappa}}_{0}/T