Fe substitution effect on the phase transition and hybridization gap in CeOs sub(2)Al sub(10)

We report on the magnetic susceptibility, electrical resistivity and specific heat measurements of the alloys Ce(Os sub(1-x)Fe sub(x)) sub(2)Al sub(10) (0 [< or =] x [< or =]1) in order to understand the anomalous phase transition in CeOs sub(2)Al sub(10) at T sub(0) = 28.5 K. With increasing x, the unit cell volume decreases linearly and the c-f hybridization is enhanced as indicated by the systematic change in the magnetic susceptibility. On the other hand, T sub(0) decreases slowly to 25 K at x = 0.3 then sharply to 20 K at x = 0.5, and eventually disappears at x = 0.6. However, the jump of C sub(p) at T sub(0), which is proportional to the entropy released by the phase transition, decreases quickly from 0.22 J/Kmol at x = 0 to 0.08 J/Kmol at x = 0.3, and then linearly to 0 at x = 0.6. These behaviours of T sub(0) resemble the pressure dependence of T sub(0) for CeOs sub(2)Al sub(10) as well as the x dependence of T sub(0) in Ce(Ru sub(1-x)Fe sub(x)) sub(2)Al sub(10) for 0.25 [< or =] x. This result suggests that the critical concentration where T sub(0) disappears depends strongly on the c-f hybridization strength.