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Name (Title):
Masanori Kohno (MANA Scientist)
Affiliation:
International Center for Materials Nanoarchitectonics
(MANA), NIMS
Address:
1-2-1 Sengen, Tsukuba. Ibaraki 305-0047, Japan
Email: KOHNO.Masanori@nims.go.jp
Home Page:
Presentation Title:
Quasiparticles in anisotropic triangular antiferromagnets
Abstract:
In usual antiferromagnets without frustrations in dimensions higher than one, spins align
antiferromagnetically. However, in the presence of strong frustrations, the antiferromagnetic
alignment is no longer stable, and can reduce to a disordered “spin liquid” state. Then,
quasiparticles (QPs) different from conventional magnons may emerge. In relation to this issue,
the anisotropic triangular antiferromagnet Cs2CuCl4 has attracted much attention, which exhibits
unusual features [1,2] distinct from those of magnons, such as large spectral weights in a wide
range of energies in dynamical structure factors and novel incommensurate orders in magnetic
fields, which have no classical analogue.
To elucidate QPs responsible for the unusual features, we applied a weak-coupling approach
from the one-dimensional (1D) limit, using exact solutions of the 1D chain [3,4]. We found that
QPs distinct from magnons and 1D QPs emerge in anisotropic triangular antiferromagnets. The
QPs are identified as bound or antibound states of 1D QPs, which do not originate from classical
long-range orders. Spectral properties of the QPs well explain unusual features observed in
Cs2CuCl4 in a unified manner as shown in Fig.1.
Fig.1 Comparisons with experimental results of Cs2CuCl4.
Solid lines denote present results. Symbols are experimental results.
References :
[1] R.Coldea et al., Phys. Rev. Lett. 86, 1335 (2001).
[2] R.Coldea et al., Phys. Rev. Lett. 79, 151 (1997).
[3] M.Kohno, O.A.Starykh and L.Balents, Nature Phys. 3, 790 (2007).
[4] M.Kohno, to appear in Phys. Rev. Lett. (2009).
Poster Session PS-11
81