Jahn-Teller distortion and magnetic transitions in perovskite RMnO3 (R=Ho, Er, Tm, Yb, and Lu)

The perovskite RMnO3 (R=Ho, Er, Tm, Yb, and Lu) were prepared under high pressure and studied with heat capacity and synchrotron x-ray powder diffraction measurements. The temperature interval between the antiferromagnetic transition and the first-order transition to the presumably E-type structure narrows with the decreasing ionic radius of R, and almost closes for R=Lu. Combined with the data for the larger rare earth R, the results show intricate relationship between the complex magnetic phase diagram and significant increase of Jahn-Teller distortion found for the smallest members of RMnO3.