arXiv subjects

J. L. Cohn

Publications and source records attributed to J. L. Cohn.

21 records · Page 2Linked to original sources

arXiv1998

Hole Localization in Underdoped Superconducting Cuprates Near 1/8th Doping

Measurements of thermal conductivity versus temperature over a broad range of doping in YBa$_2$Cu$_3$O$_{6+x}$ and HgBa$_2$Ca$_{n-1}$Cu$_n$O$_{2n+2+δ}$ ($n$=1,2,3) suggest that small domains of localized holes develop for hole concentrations near $p$=1/8. The data imply a mechanism for localization that is intrinsic to the CuO$_2$-planes and is enhanced via pinning associated with oxygen-vacancy clusters.

cond-mat.supr-con↗

arXiv1998

Thermal Transport as a Probe of Localized Charge and Lattice Distortions in Manganites and Cuprates

The thermal resistivity of manganites and cuprates is shown to correlate with local lattice distortions and the presence of localized holes as determined from neutron diffraction and nuclear quadrupole resonance. Oxygen doping dependent studies of heat conduction in Y-123 and Hg cuprates suggest that a fraction of the holes in the CuO$_2$ planes are localized near the planar hole concentration $p=1/8$. The results are consistent with the formation of short-ranged, static stripe domains that are pinned near oxygen vacancy clusters.

cond-mat.supr-con↗

arXiv1998

Anisotropic in-plane thermal conductivity of single-crystal YBa_2Cu_4O_8

We report measurements of the in-plane thermal conductivity ($κ$) of YBa_2Cu_4O_8 (Y-124) single crystals in the temperature range $4K\leq T\leq 300K$ and compare them with previous results on YBa_2Cu_3O_{6+x} (Y-123). For transport perpendicular to the CuO chains, $κ_a(300K)\simeq 10$W/mK, and along the chains, $κ_b(300K)\simeq 40$W/mK. The temperature dependence of $κ$ for both transport directions is much stronger than in YBa_2Cu_3O_{6+x} (Y-123), indicative of substantially superior lattice heat conduction in Y-124, and resulting in maximum values for $κ$ at $T\sim 20$K exceeding 200W/mK. The data imply a surprisingly large anisotropy in the lattice conduction. $κ_a$ and $κ_b$ are enhanced in the superconducting state as in other cuprates. The magnitude and anisotropy of the enhancement are discussed and compared to those of Y-123.

cond-mat.supr-con↗