A tunable stress dilatometer and measurement of the thermal expansion under uniaxial stress of Mn3Sn

We present a method for measuring thermal expansion under tunable uniaxial stresses and show measurements of the thermal expansion of Mn3Sn, a room temperature antiferromagnet that exhibits a spontaneous Hall effect, under uniaxial stresses of up to 1.51 GPa compression. The measurement of thermal expansion provides thermodynamic data about the nature of phase transitions, and uniaxial stress provides a powerful tuning method that does not introduce disorder. Mn3Sn exhibits an anomaly in its thermal expansion near ∼270 K, associated with a first-order change in its magnetic structure. We show that this transition temperature is suppressed by 54.6 K by 1.51 GPa compression along [0001]. We find the associated entropy change at the transition to be ∼ 0.1 J mol−1 K−1 and to vary only weakly with applied stress.