Thermal expansion under uniaxial pressure in URuSi

Kambe, Shinsaku  ; Aoki, Dai*; Salce, B.*; Bourdarot, F.*; Braithwaite, D.*; Flouquet, J.*; Brison, J.-P.*

The temperature dependence of the thermal expansion coefficient has been measured in URuSi under uniaxial pressure along the [100] and [110] directions up to GPa. For both cases, the hidden order phase transition temperature increases with increasing uniaxial pressure. An anomaly of the thermal expansion coefficient at appears to be enhanced under a small uniaxial pressure ( GPa). An antiferromagnetically ordered phase appears at above the critical pressure GPa for uniaxial pressure along the [100] direction, whereas no antiferromagnetic transition is detected up to GPa for uniaxial pressure along the [110] direction, indicating that the critical pressure is beyond GPa for the [110] case.