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Thermal expansion and thermodynamic characterization of antiferromagnetic phase transition in elemental α ‐Mn
Author(s) -
White B. D.,
Bollinger R. K.,
Neumeier J. J.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451247
Subject(s) - antiferromagnetism , thermal expansion , bulk modulus , condensed matter physics , phase transition , thermodynamics , materials science , specific heat , thermal , phase (matter) , volume (thermodynamics) , negative thermal expansion , heat capacity , characterization (materials science) , chemistry , physics , nanotechnology , organic chemistry
High‐resolution measurements of thermal expansion and specific heat have been performed on α ‐Mn. An analysis of these thermodynamic properties, with particular emphasis on their behavior in the temperature region near the Néel temperature, T N = 101.4(2) K, suggests that the antiferromagnetic phase transition is continuous (second order within the Ehrenfest classification scheme). The thermal expansion for T ≲ T N is negative, which is probably related to the volume dependence of the magnetic exchange interactions. This is manifested in the negative pressure derivative d T N / d P and may also be related to the anomalously low reported values of the bulk modulus for α ‐Mn. Large, negative values of the bulk Grüneisen function, γ G , for T < 75 K are comparable to those of antiferromagnetic Cr. In each case, the magnetic contribution to γ G dominates for T ≤ T N .