- Tytuł:
- Magnon and Soliton Excitations in the Carrier-Poor, One-Dimensional S=1/2 Antiferromagnet Yb$\text{}_{4}$As$\text{}_{3}$
- Autorzy:
-
Steglich, F.
Köppen, M.
Gegenwart, P.
Cichorek, T.
Wand, B.
Lang, M.
Thalmeier, P.
Schmidt, B.
Aoki, H.
Ochiai, A. - Powiązania:
- https://bibliotekanauki.pl/articles/2011226.pdf
- Data publikacji:
- 2000-01
- Wydawca:
- Polska Akademia Nauk. Instytut Fizyki PAN
- Tematy:
-
75.30.Mb
65.50.+m
65.70.+y - Opis:
- The semimetallic quasi-one-dimensional S=1/2 Heisenberg antiferromagnet Yb$\text{}_{4}$As$\text{}_{3}$ was studied by low-temperature measurements of the specific heat C(T,B), thermal expansion α(T,B), and thermal conductivity ĸ(T,B). At finite magnetic fields (B≤12 T) we observed the following distinct anomalies: (1) the magnon contribution to C(T,0), γ T, with large coefficient γ ≈ 200 mJ/(K$\text{}^{2}$mol), becomes strongly reduced with field, and (2) a broad hump in C(T,B=const) is induced at slightly higher temperatures. (3) The latter corresponds to a pronounced peak in α(T,B=const) as well as (4) to a broad minimum in ĸ(T,B= const)/ĸ(T,0). These anomalies are well described by the classical sine-Gordon solution of a one-dimensional Heisenberg antiferromagnet with a weak easy-plane anisotropy. However, the soliton-rest energy deduced from the experimental results depends on the magnetic field like E$\text{}_{S}$ ~ B$\text{}^{ν}$, with an exponent ν ≈ 0.66, while the classical sine-Gordon model requires ν=1. Thus, our results suggest an alternative description of soliton excitations in an antiferromagnetic S=1/2 Heisenberg chain in terms of the quantum sine-Gordon model, for which an exponent ν=2/3 is appropriate.
- Źródło:
-
Acta Physica Polonica A; 2000, 97, 1; 91-100
0587-4246
1898-794X - Pojawia się w:
- Acta Physica Polonica A
- Dostawca treści:
- Biblioteka Nauki
Artykuł