Coexistence of Haldane-gap excitations and long-range antiferromagnetic order in mixed-spin nickelates R{sub 2}BaNiO{sub 5}

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.57.68· OSTI ID:565868

Maslov, S; Zheludev, A ^[1]

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1. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

The spin dynamics of the S=1 Ni chains in mixed-spin antiferromagnets Pr{sub 2}BaNiO{sub 5} and Nd{sub x}Y{sub 2{minus}x}BaNiO{sub 5} is described in terms of a simple Ginzburg-Landau Lagrangian coupled to the sublattice of rare-earth ions. Within this framework we obtain a theoretical explanation for the experimentally observed coexistence of Haldane-gap excitations and long-range magnetic order, as well as for the increase of the Haldane-gap energy below the N{acute e}el point. We also predict that the degeneracy of the Haldane triplet is lifted in the magnetically ordered phase. The growth of both gaps are shown to follow from the magnon repulsion. The theoretical results are consistent with the available experimental data. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 565868
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 1 Vol. 57; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
ANTIFERROMAGNETISM
BARIUM OXIDES
ENERGY GAP
GINZBURG-LANDAU THEORY
MAGNETIC PROPERTIES
MAGNONS
NEEL TEMPERATURE
NICKEL OXIDES
PRASEODYMIUM OXIDES
SPIN
YTTRIUM OXIDES