Compositional dependence of transport anisotropy in large (La, Sr)2CuO4 single crystals and second peak in magnetization curves

✍ Scribed by Tsuyoshi Kimura; Kohji Kishio; Tsutomu Kobayashi; Yoshimi Nakayama; Naobumi Motohira; Koichi Kitazawa; Kaoru Yamafuji

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 573 KB
• Volume: 192
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90767-7

✦ Synopsis

Large single crystals of (Lat_~Sr~)2CuO4, up to 5 mm along the crystal c-axis, have been grown over a composttion range of x=0.03 to 0.15, covering the ~vhole superconducting region in this system. A complete set of electrical resistivity data along both the c-axis (pc) and ab-plane (Pob) have been obtained via the DC four-probe method for the first time. As x was varied, both resistivities changed monotonically from semiconductive to metallic in character and the critical temperature, T,, defined by the mid-point of the resistive transition curves, passed through a maximum value of 38.8 K at x=0.072. The amsotropy ratio PJP,,b at 50 K decreased drastically with increasing x, from nearly 4000 to 160, while it was approximately 350 at x= 0.072. Magnetization hysteresis curves (HIIc,+ 9 T) revealed the presence of an additional pinning mechanism in the over-do; -d re,on tx >/0.072 ) giving rise to a second peak at moderately high fields. This was attributed to enhanced flux pmnmg by oxygen vacancies nominally present in this composition range.