Specific heat at low temperatures of ultrastable glasses of TPD
ORAL
Abstract
Glasses exhibit thermal, vibrational and acoustic properties at low temperatures anomalously different from those found in crystalline solids, and with a remarkable degree of universality [1].
Interestingly, our earlier low-temperature specific-heat measurements on (highly anisotropic) ultrastable glasses of indomethacin prepared by Physical Vapour Deposition (PVD) [2] showed the suppression of the ubiquitous linear term below 1-2 K traditionally ascribed to the existence of tunneling two-level systems (TLS) in glasses [3]. This finding apparently challenged the opposite behavior found in hyperaged glasses of geological amber [4].
Here we will present the results of our ongoing experiments of low-temperature specific heat, as well as of Brillouin Scattering, on a different ultrastable glass, TPD, whose degree of anisotropy can be controlled. We aim at comparing its behavior at low temperatures to that of its conventional glass and crystalline states.
[1] W. A. Phillips, ed., Amorphous Solids, Low-Temperature Properties, Springer (1981)
[2] M. D. Ediger, J. Chem. Phys. 147, 210901 (2017)
[3] T. Pérez-Castañeda, C. Rodríguez-Tinoco, J. Rodríguez-Viejo, M. A. Ramos, PNAS 111, 11275 (2014)
[4] T. Pérez-Castañeda, R. J. Jiménez-Riobóo, M. A. Ramos, Phys. Rev. Lett. 112, 165901 (2014)
Interestingly, our earlier low-temperature specific-heat measurements on (highly anisotropic) ultrastable glasses of indomethacin prepared by Physical Vapour Deposition (PVD) [2] showed the suppression of the ubiquitous linear term below 1-2 K traditionally ascribed to the existence of tunneling two-level systems (TLS) in glasses [3]. This finding apparently challenged the opposite behavior found in hyperaged glasses of geological amber [4].
Here we will present the results of our ongoing experiments of low-temperature specific heat, as well as of Brillouin Scattering, on a different ultrastable glass, TPD, whose degree of anisotropy can be controlled. We aim at comparing its behavior at low temperatures to that of its conventional glass and crystalline states.
[1] W. A. Phillips, ed., Amorphous Solids, Low-Temperature Properties, Springer (1981)
[2] M. D. Ediger, J. Chem. Phys. 147, 210901 (2017)
[3] T. Pérez-Castañeda, C. Rodríguez-Tinoco, J. Rodríguez-Viejo, M. A. Ramos, PNAS 111, 11275 (2014)
[4] T. Pérez-Castañeda, R. J. Jiménez-Riobóo, M. A. Ramos, Phys. Rev. Lett. 112, 165901 (2014)
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Presenters
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Miguel Ramos
- Condensed Matter Physics Department, Universidad Autonoma de Madrid