Field and Impurity Induced Ordering in Interacting Dimer Systems

We study the interplay of doping and an external magnetic field H on dimerized antiferromagnetic S = 1/2 systems with a finite spin gap Δ. We show that for sufficiently small three-dimensional coupling J′ the long-range antiferromagnetic order known to result from doping with nonmagnetic impurities...

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Bibliographic Details
Published inProgress of theoretical physics. Supplement Vol. 159; no. 159; pp. 376 - 386
Main Authors Mikeska, Hans-Jürgen, Kolezhuk, Alexei
Format Journal Article
LanguageEnglish
Published Kyoto Oxford University Press 01.01.2005
Progress of Theoretical Physics
Subjects
Exact sciences and technology
Physics
Antiferromagnetism
Phase diagrams
Weak coupling
Critical field
Magnetic fields
Long-range order
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Summary:We study the interplay of doping and an external magnetic field H on dimerized antiferromagnetic S = 1/2 systems with a finite spin gap Δ. We show that for sufficiently small three-dimensional coupling J′ the long-range antiferromagnetic order known to result from doping with nonmagnetic impurities is destroyed by a weak magnetic field H>Hc1. The lower critical field Hc1 is proportional to the impurity concentration, above Hc1 the system remains in the disordered (plateau) phase up to the much higher upper critical field Hc2 ≃Δ. We discuss the phase diagram in the (H,J') and (H,T) planes and suggest that the reentrant behavior can be experimentally observed in KCuCl3. It is argued that similar phenomena can arise in other weakly coupled quasi-one-dimensional gapped systems.
ISSN:0375-9687
DOI:10.1143/PTPS.159.376