Influence of Mn-site doping upon orbital and charge ordering in the Pr0.5A0.5Mn1-xMxO3 manganites (A = Sr, Ca and M = Cr, Al)

The influence of Cr and Al-doping upon orbital and charge ordering in Pr(0.5)A(0.5)MnO(3) manganites (A = Sr, Ca) has been investigated combining magnetic and transport measurements with neutron powder diffraction and electron microscropy. It is shown that Cr-doping induces or reinforces the ferromagnetic metallic state, and destroys the ordering and associated antiferromagnetism whatever is its nature, A or CE-type. On the contrary, the orbital and charge ordering and associated antiferromagnetic ground states are essentially retained after doping with diamagnetic aluminium. Moreover, the Al-doping in Pr0.5Sr0.5MnO3 expands the antiferromagnetic region and suppresses the ferromagnetism at intermediate temperatures. (C) 1999 Elsevier Science B.V. All rights reserved.