Microtwin Domains and Phase Transitions in La1.85−x Ndx Sr0.15 CuO4

Abstract

Microstructural phenomena and phase transitions of the Nd‐doped La1.85 Sr0 15 CuO4 system are studied in an electron microscope. In ion‐milled samples, twin domains appear and disappear as expected at the high temperature phase transition. At temperatures below the high temperature transition, these twin domains show a very subtle behaviour. Ground material even in the orthorhombic phase shows no twins at all. In ion‐thinned material a typical reduction of the domain size occurs after an electron illumination time of about one hour. Generally no reversible change of the twin configuration could be observed at the low temperature phase transition.

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

“…It was initially thought that, since the LTT phase is tetragonal, this transition should be clearly marked by the disappearence of twinning in the LTT phase. Instead, there appeared to be no change in the pattern of twins at the transition [455,456]. In fact, the LTT phase has orthorhombic symmetry within a single CuO 2 layer, but the global symmetry becomes orthorhombic due to the interlayer stacking.…”