Negative thermal expansion of MgB$_{2}$ in the superconducting state and anomalous behavior of the bulk Grüneisen function

J. J. Neumeier; T. Tomita; M. Debessai; J. S. Schilling; P. W. Barnes; D. G. Hinks; J. D. Jorgensen

doi:10.1103/physrevb.72.220505

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Negative thermal expansion of MgB$_{2}$ in the superconducting state and anomalous behavior of the bulk Grüneisen function

J. J. Neumeier·T. Tomita·M. Debessai·J. S. Schilling·P. W. Barnes·D. G. Hinks·J. D. Jorgensen

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Abstract

The thermal expansion coefficient $α$ of MgB$_2$ is revealed to change from positive to negative on cooling through the superconducting transition temperature $T_c$. The Grüneisen function also becomes negative at $T_c$ followed by a dramatic increase to large positive values at low temperature. The results suggest anomalous coupling between superconducting electrons and low-energy phonons.

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J. J. Neumeier, T. Tomita, M. Debessai, J. S. Schilling, P. W. Barnes, D. G. Hinks, J. D. Jorgensen. 2005-10-19. Negative thermal expansion of MgB$_{2}$ in the superconducting state and anomalous behavior of the bulk Grüneisen function. https://doi.org/10.1103/physrevb.72.220505

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