Relation between crystal and magnetic structures of layered manganite La2-2xSr1+2xMn2O7 (0.30 ≤ x ≤ 0.50)

The magnetic phase diagram of La2-2xSr1+2xMn2O7 (0.30 less than or equal to x less than or equal to 0.50) was reexamined from the point of view of the crystal structure, particularly the Jahn-Teller (JT) distortion Delta(JT) of Mn-O-6 octahedra, i.e., the ratio of the averaged apical Mn-O bond length. to the equatorial Mn-O bond length. We have found that Delta(JT) decreases with increasing hole concentration x. while the canting angle between neighboring planes continuously increases from 0 degrees (planar ferromagnet: 0.32 less than or equal to x less than or equal to 0.38) to 180 degrees (A-type antiferromagnet (AFM): x = 0.48). The dominance of the A-type AFM structure with the decrease of Delta(JT) call be ascribed to the change in the epsilon(g) orbital State from d(3z2-x2) to d(x2-y2).