Phonon energy gaps in the charged incommensurate planes of the spin-ladder Sr14Cu24O41 compound by Raman and infrared spectroscopy

• Published in: Physical review letters 2012-05, Vol.108 (21), p.217401-217401
• Main Authors: Thorsmølle, V K, Homes, C C, Gozar, A, Blumberg, G, van Mechelen, J L M, Kuzmenko, A B, Vanishri, S, Marin, C, Rønnow, H M
• Format: Article
• Language: English
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.108.217401

The terahertz (THz) excitations in the quantum spin-ladder system Sr14Cu24O41 have been determined along the c axis using THz time-domain, Raman, and infrared spectroscopy. Low-frequency infrared and Raman active modes are observed above and below the charge-ordering temperature T(co) is approximately equal to 200 K over a narrow interval approximately equal to 1-2 meV approximately equal to 8-16 cm(-1)). A new infrared mode at approximately equal to 1 meV develops below approximately equal to 100 K. The temperature dependence of these modes shows that they are coupled to the charge- and spin-density-wave correlations in this system. These low-energy features are conjectured to originate in the gapped sliding motion of the chain and ladder subsystems, which are both incommensurate and charged.