arXiv subjects

Pengcheng Li

Publications and source records attributed to Pengcheng Li.

94 records · Page 6Linked to original sources

arXiv2007

Upper critical field of electron-doped Pr$_{2-x}$Ce$_x$CuO$_{4-δ}$ in parallel magnetic fields

We report a systematic study of the resistive superconducting transition in the electron-doped cuprates Pr$_{2-x}$Ce$_{x}$CuO$_{4-δ}$ down to 1.5 K for magnetic field up to 58 T applied parallel to the conducting ab-planes. We find that the zero temperature parallel critical field (H$_{c2\parallel ab}$(0)) exceeds 58 T for the underdoped and optimally-doped films. For the overdoped films, 58 T is sufficient to suppress the superconductivity. We also find that the Zeeman energy $μ_B$H$_{c2\parallel ab}$(0) reaches the superconducting gap ($\triangle_0$), i.e. $μ_B$H$_{c2\parallel ab}(0)\simeq \triangle_0$, for all the dopings, strongly suggesting that the parallel critical field is determined by the Pauli paramagnetic limit in electron-doped cuprates.

cond-mat.supr-con↗

arXiv2007

Evidence for a quantum phase transition in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4-δ}$ from Thermopower measurements

The evidence for a quantum phase transition under the superconducting dome in the high-$T_c$ cuprates has been controversial. We report low temperature normal state thermopower(S) measurements in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4-δ}$ as a function of doping (x from 0.11 to 0.19). We find that at 2K both S and S/T increase dramatically from x=0.11 to 0.16 and then saturate in the overdoped region. This behavior has a remarkable similarity to previous Hall effect results in Pr$_{2-x}$Ce$_{x}$CuO$_{4-δ}$ . Our results are further evidence for an antiferromagnetic to paramagnetic quantum phase transition in electron-doped cuprates near x=0.16.

cond-mat.supr-con↗

arXiv2007

Correlation between incoherent phase fluctuations and disorder in Y$_{1-x}$Pr$_x$Ba$_2$Cu$_3$O$_{7-δ}$ epitaxial films from Nernst effect measurements

Measurements of Nernst effect, resistivity and Hall angle on epitaxial films of Y$_{1-x}$Pr$_x$Ba$_2$Cu$_3$O$_{7-δ}$(Pr-YBCO, 0$\leq x\leq$0.4) are reported over a broad range of temperature and magnetic field. While the Hall and resistivity data suggest a broad pseudogap regime in accordance with earlier results, these first measurements of the Nernst effect on Pr-YBCO show a large signal above the superconducting transition temperature(T$_c$). This effect is attributed to vortex-like excitations in the phase incoherent condensate existing above T$_c$. A correlation between disorder and the width of the phase fluctuation regime has been established for the YBCO family of cuprates, which suggests a T$_c\approx$110K for disorder-free YBa$_2$Cu$_3$O$_{7-δ}$.

cond-mat.supr-con↗

arXiv2007

High-field Hall resistivity and magnetoresistance in electron-doped Pr_2-xCe_xCuO_{4-δ}

We report resistivity and Hall effect measurements in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4-δ}$ films in magnetic field up to 58 T. In contrast to hole-doped cuprates, we find a surprising non-linear magnetic field dependence of Hall resistivity at high field in the optimally doped and overdoped films. We also observe a crossover from quadratic to linear field dependence of the positive magnetoresistance in the overdoped films. A spin density wave induced Fermi surface reconstruction model can be used to qualitatively explain both the Hall effect and magnetoresistance.

cond-mat.supr-con↗