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High-resolution measurements of thermal expansion and specific heat have been performed on -Mn. An analysis of these thermodynamic properties, with particular emphasis on their behavior in the temperature region near the Neel temperature, = 101.4(2) K, suggests that the antiferromagnetic phase transition is continuous (second order within the Ehrenfest classification scheme). The thermal expansion for is negative, which is probably related to the volume dependence of the magnetic exchange interactions. This is manifested in the negative pressure derivative and may also be related to the anomalously low reported values of the bulk modulus for -Mn. Large, negative values of the bulk Gruneisen function, , for 75 K are comparable to those of antiferromagnetic Cr. In each case, the magnetic contribution to dominates for . |
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