Abstract
Abstract
The effect of partially substituting Tin (Sn) at the Manganese (Mn) site of
Ca
3
Mn
2
O
7
, viz.
Ca
3
Mn
2
−
x
Sn
x
O
7
with
x
=
0.03
,
0.05
, on its structural and magnetic properties have been investigated using synchrotron diffraction, neutron diffraction, and bulk magnetization measurements. It is observed that with a substitution of
x
=
0.03
, the minor (≈8%) tetragonal (
I
4
/
m
m
m
) structural phase that is present in the predominantly orthorhombic (
C
m
c
2
1
) undoped
Ca
3
Mn
2
O
7
, completely disappears. The compounds order antiferromagnetically, the ordering temperature decreases with increasing Sn-content, indicating a weakening of the antiferromagnetic exchange interactions. Interestingly, in the ordered state, the spin magnetic moments which were aligned along the a-axis of the unit cell in the undoped compound, are observed to have reoriented with their major components lying in the b − c plane in the Sn-doped compounds. The above influence of Sn-doping is seen to be stemming from a significant modification of the octahedral rotation and tilt mode geometry in the unit cell, that is known to be responsible for driving ferroelectricity in these compounds.
Funder
UGC-DAE Consortium for Scientific Research, University Grants Commission
Department of Science and Technology, Ministry of Science and Technology, India