  In the recently discovered heavy fermion superconductor CeRh2As2, a magnetic
field induced phase transition has been observed inside the superconducting
state, which is proposed to be a transition from an even to an odd-parity
superconducting state. The odd-parity superconducting state and its large upper
critical field has been explained by local inversion symmetry breaking and
consequent Rashba spin-orbit coupling. Here we report the experimental tuning
of the parity of superconductivity in CeRh2As2 via applied pressure.
Superconductivity is enhanced by pressure after its initial suppression,
forming a second dome. However, the odd-parity state only exists in the first
dome and the second dome is dominated by the even-parity state. This parity
switch of superconductivity under pressure is consistent with the competition
between Rashba spin-orbit coupling and interlayer hopping in determining the
parity of superconductivity in systems with local inversion symmetry breaking.
Our results provide insightful guidance on how to look for new odd-parity
superconductors.
