title: Tuning of the spin gap transition of spin dimer compound Ba(3)Mn(2)O(8) by doping with La and V.
abstract: We have successfully synthesized the coupled spin dimer systems La(x)Ba(3-x)Mn(2)O(8) (x = 0, 0.2, 0.5, 1) and Ba(3)Mn(2-y)V(y)O(8) (y = 0.5, 1.0, 2.0). The magnetic properties have been investigated as a function of magnetic field and temperature down to 2 K. The susceptibility increases and the intradimer spin exchange interaction decreases with increase of La concentration. The most important finding in higher La doped systems reveals hysteresis in magnetization as a function of magnetic field. The substitution of La (x = 0.5, 1.0) for Ba induces ferromagnetism due to the formation of a mixed valence state of Mn and enhancement of the inter-bilayer ferromagnetic interaction. The replacement of Mn by non-magnetic V destroys the spin gap. La and V doping significantly affect the magnetic properties of the quantum antiferromagnetic compound Ba(3)Mn(2)O(8).
authors.affiliation: Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India. Centre for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
authors.forename: S
authors.initials: S
authors.lastname: Manna
authors.forename: S
authors.initials: S
authors.lastname: Majumder
authors.forename: S K
authors.initials: SK
authors.lastname: De