First- and second-order phase transitions between the uniform and FFLO excitonic states in the three-chain Hubbard model for Ta2NiSe5

We examine the free energy and the thermodynamic properties in the three-chain Hubbard model for Ta2NiSe5 to clarify the phase transitions between the uniform and the FFLO excitonic states which are expected to be observed in Ta2NiSe5 under high pressure.