Suppression of tunneling two-level systems in ultrastable glasses of indomethacin

Tomás Pérez-Castañeda, Cristian Rodríguez-Tinoco, Javier Rodríguez-Viejo, Miguel A. Ramos

Research output: Contribution to journalArticleResearchpeer-review

110 Citations (Scopus)


Glasses and other noncrystalline solids exhibit thermal and acoustic properties at low temperatures anomalously different from those found in crystalline solids, and with a remarkable degree of universality. Below a few kelvin, these universal properties have been successfully interpreted using the tunneling model, which has enjoyed (almost) unanimous recognition for decades. Here we present low-temperature specific-heat measurements of ultrastable glasses of indomethacin that clearly show the disappearance of the ubiquitous linear contribution traditionally ascribed to the existence of tunneling twolevel systems (TLS). When the ultrastable thin-film sample is thermally converted into a conventional glass, the material recovers a typical amount of TLS. This remarkable suppression of the TLS found in ultrastable glasses of indomethacin is argued to be due to their particular anisotropic and layered character, which strongly influences the dynamical network and may hinder isotropic interactions among low-energy defects, rather than to the thermodynamic stabilization itself. This explanation may lend support to the criticisms by Leggett and others [Yu CC, Leggett AJ (1988) Comments Condens Matter Phys 14(4):231-251; Leggett AJ, Vural DC (2013) J Phys Chem B 117(42):12966-12971] to the standard tunneling model, although more experiments in different kinds of ultrastable glasses are needed to ascertain this hypothesis.
Original languageEnglish
Pages (from-to)11275-11280
JournalProceedings of the National Academy of Sciences of the United States of America
Publication statusPublished - 5 Aug 2014


  • Glass transition
  • Glassy anomalies
  • Low-temperature properties of glasses
  • Organic glasses


Dive into the research topics of 'Suppression of tunneling two-level systems in ultrastable glasses of indomethacin'. Together they form a unique fingerprint.

Cite this