Thermal conductivity of lightly Sr- and Zn-doped La2CuO4 single crystals -: art. no. 104503

Both ab-plane and c-axis thermal conductivities (kappa(ab) and kappa(c)) of lightly doped La2-xSrxCuO4 (LSCO) and La2Cu1-yZnyO4 single crystals (x or y = 0-0.04) are measured from 2 to 300 K. It is found that the low-temperature phonon peak (at 20-25 K) is significantly suppressed upon Sr or Zn doping even at very low doping, though its precise doping dependences show interesting differences between the Sr and Zn dopants, or between the ab plane and the c axis. Most notably, the phonon peak in kappa(c) decreases much more quickly with Sr doping than with Zn doping, while the phonon-peak suppression in kappa(ab) shows an opposite trend. It is discussed that the scattering of phonons by stripes is playing an important role in the damping of the phonon heat transport in lightly doped LSCO, in which static spin stripes have been observed by neutron scattering. We also show kappa(ab) and kappa(c) data of La1.28Nd0.6Sr0.12CuO4 and La1.68Eu0.2Sr0.12CuO4 single crystals to compare with the data of the lightly doped crystals for the discussion of the role of stripes. At high temperature, the magnon peak (i.e., the peak caused by the spin heat transport near the Neel temperature) in kappa(ab)(T) is found to be rather robust against Zn doping, while it completely disappears with only 1% of Sr doping.