Upper critical field H_c2 in PrOs₄Sb₁₂

We study the upper critical field of the A and B phases in the triplet superconductor PrOs₄Sb₁₂ within the p + h-wave superconductivity proposed recently for this material. The present result is compared with H_c2(t) and H*(t), the boundary between the A and B phase in PrOs₄Sb₁₂, reported earlier [Measson et al., Phys. Rev. B 70, 064516 (2004)] and with more recent data of H_c2(t) for the single phase crystal. We find H_c2(t)'s for both the two phase crystal and the single phase crystal are described by the model for the A phase. From this fitting one can deduce the Fermi velocity as v = 2.5 × 10⁶ cm/s. On the other hand H_c2(t) for the B phase is found to be somewhat smaller than H*(t), which indicates that H*(t) belongs to the A phase.