Structural and magnetization study of Pr1−xCaxMnO3

Orbital and charge ordering inPr1−xCaАнисимов1, Elfimov2, Korotin3 et al. 1997Phys. Rev. B702380View full textAdd to dashboardCite

“…This is in a striking agreement with the orbital order derived in [8] from the neutron diffraction mesuarements (Fig.4). The unexpected result is that the total number of d-electrons at all types of Mn sites are nearly equal (4.99 and 5.01), so that formally Mn 4+ ions (in the Fig.3 the ones with symmetric in-plane density distribution) and Mn 3+ ions (the ones with the density strongly anisotropic) have nearly the same number of 3d-electrons.…”

“…The crystal structure of the doped Pr 1−x Ca x MnO 3 does not show transition to the rombohedral symmetry, as it is the case for La 1−x Sr x MnO 3 , preserving the orthorombic P bnm space group [8]. However the values of the lattice parameters a,b and c/ √ 2 for x=0.5 are so close that it can be called a pseudocubic structure.…”

“…Their idea is that a E JT /W ratio (E JT is self- [8,9]. At low temperature, it is an antiferromagenetic insulator with a charge ordering of Mn 3+ and Mn 4+ accompanied by an orbital ordering: the orbital ordering and spin ordering is of CE-type.…”

Ferromagnetism, insulator-metal transition and magnetotransport in Pr0.58Ca0.42MnO3films: role of microstructural perturbations

“…At commensurate carrier concentration (x=0.5), the COI state persists down to the lowest temperatures even at magnetic field as high as H=120 kOe but the phase boundaries shift towards lower magnetic fields at incommensurate carrier concentrations (x=0.4, 0.35 and 0.3) [7]. The neutron diffraction studies by Zirak et al [10,11] have demonstrated that as the carrier concentration changes from commensurate to incommensurate levels the spin arrangement within the a-b plane preserves the CE-type feature but that along the c direction changes from antiparallel to parallel. The evolution of such spin order has been discussed in terms of the FM double exchange (DE) interaction along the c direction mediated by the extra electrons.…”

“…In general the ferromagnetic metal (FMM) phase is realized via COI to FMM phase transformation only under the influence of external perturbations like magnetic field [3][4][5][6][7][8]. The magnetic field required for COI-FMM phase transformation (CO melting field) is dependent on x and is reduced drastically as x is lowered from ~0.5 towards ~0.3 [9,10]. At commensurate carrier concentration (x=0.5), the COI state persists down to the lowest temperatures even at magnetic field as high as H=120 kOe but the phase boundaries shift towards lower magnetic fields at incommensurate carrier concentrations (x=0.4, 0.35 and 0.3) [7].…”