Stripes in heterovalent metal-doped cuprates

Manfred Bucher

paper

Stripes in heterovalent metal-doped cuprates

arXiv:2002.12116

Abstract

Doping $L a_{2} C u O_{4}$ with alkaline-earth, $A e = S r, B a$ generates holes in $L a_{2 - y - x} L n_{y} A e_{x} C u O_{4}$ ( $L n =$ $N d, E u$ ). A small fraction of the holes, $p ˇ \leq$ $0.02$ , suppresses 3D-AFM. The rest resides as double holes at $O$ atoms in the $C u O_{2}$ planes. The superlattice, formed by the $O$ atoms, gives rise to both charge order stripes and magnetization stripes with incommensurability $q_{c, m} (x) \propto x - p ˇ$ for $A e$ doping $x < x^$ , but constant $q_{c}$ beyond. Antiparallel orientation of magnetic moments $m (O)$ yields a natural explanation for the coupling of $q_{m} (x) = \frac{1}{2} q_{c} (x)$ . Doping $N d_{2} C u O_{4}$ with $C e$ generates electrons that reside pairwise in copper atoms. This accounts for the different properties of $n$ -doped compounds. When $n$ -doped, $q_{c} (x) \propto x$ . Above a threshold temperature $T^{'}$ , electron-hole pairs are thermally generated, but then separate to reside pairwise at $C u$ and $O$ atoms. This breaks the locking of the incommensurability of charge order and magnetization stripes, $q_{m} (x) \neq = \frac{1}{2} q_{c} (x)$ .

29 pages, 4 figures, 3 tables, 2 appendices. Change from the previous version: Minor corrections in Figs. 1 and 2