Abstract
We have studied the behavior of the thermal expansion coefficient α(T) (in a zero magnetic field and at H≈4 T), the heat capacity C(T), and the thermal conductivity κ(T) of magnesium boride (MgB2) in the vicinity of T c and at lower temperatures. It was established that MgB2, like oxide-based high-temperature superconductors, exhibits a negative thermal expansion coefficient at low temperatures. The anomaly of α(T) in MgB2 is significantly affected by the magnetic field. It was established that, in addition to the well-known superconducting transition at T c≈40 K, MgB2 exhibits an anomalous behavior of both heat capacity and thermal conductivity in the region of T≈10–12 K. The anomalies of C(T) and κ(T) take place in the same temperature interval where the thermal expansion coefficient of MgB2 becomes negative. The low-temperature anomalies are related to the presence of a second group of charge carriers in MgB2 and to an increase in the density of the Bose condensate corresponding to these carriers at T c2≈10–12 K.
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Translated from Zhurnal Éksperimental’no\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l}\) i Teoretichesko\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l}\) Fiziki, Vol. 124, No. 1, 2003, pp. 80–88.
Original Russian Text Copyright © 2003 by Anshukova, Bulychev, Golovashkin, Ivanova, Krynetski\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l}\), Minakov, Rusakov.
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Anshukova, N.V., Bulychev, B.M., Golovashkin, A.I. et al. Anomalous low-temperature behavior of the thermal characteristics of MgB2 . J. Exp. Theor. Phys. 97, 70–77 (2003). https://doi.org/10.1134/1.1600798
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DOI: https://doi.org/10.1134/1.1600798