Crystal growth and thermodynamic properties of (Ca, La)14Cu24O41

High quality, centimeter size single crystals of Ca14−xLaxCu24O41have been successfully grown using the travelling solvent floating zone (TSFZ) method in association with an image furnace. Crystals grown under oxygen pressures up to 13 bar are single phase for 2 ≤ x ≤ 5. Growth initiated on a single crystalline seed, in combination with an appropriate solvent disk, yields a single domain almost directly from the beginning of the growth. Crystals were characterized by EDX, TGA and X-ray powder diffraction. In addition magnetic susceptibility and specific heat measurements were performed. Long range antiferromagnetic order occurs at TN=9.7 K for xLa = 5, whereas for lower La concentrations TNis considerably suppressed.