Charge-order-induced sharp Raman peak in Sr14Cu24O41

K P Schmidt; C Knetter; M Grüninger; G S Uhrig

doi:10.1103/PhysRevLett.90.167201

Charge-order-induced sharp Raman peak in Sr14Cu24O41

Phys Rev Lett. 2003 Apr 25;90(16):167201. doi: 10.1103/PhysRevLett.90.167201. Epub 2003 Apr 21.

Authors

K P Schmidt¹, C Knetter, M Grüninger, G S Uhrig

Affiliation

¹ Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany.

PMID: 12731999
DOI: 10.1103/PhysRevLett.90.167201

Abstract

In the two-leg S=1/2 ladders of Sr14Cu24O41, a modulation of the exchange coupling arises from the charge order within the other structural element, the CuO2 chains. In general, breaking transla-tional invariance by modulation causes gaps within the dispersion of elementary excitations. We show that the gap induced by the charge order can drastically change the magnetic Raman spectrum, leading to the sharp peak observed in Sr14Cu24O41. This sharp Raman line gives insight into the charge-order periodicity and hence into the distribution of carriers. The much broader spectrum of La6Ca8Cu24O41 reflects the response of an undoped ladder in the absence of charge order.