Low energy singlets in the excitation spectrum of the spin tetrahedra system Cu2Te2O5Br2

被引：12

作者：

Lemmens, P

Choi, KY

Ionescu, A

Pommer, J

Güuntherodt, G

Valenti, R

Gros, C

Brenig, W

Johnson, M

Millet, P

Mila, F

机构：

[1] Rhein Westfal TH Aachen, Inst Phys 2, D-52056 Aachen, Germany

[2] Tech Univ Carolo Wilhelmina Braunschweig, IMNF, D-38106 Braunschweig, Germany

[3] Univ Saarland, Inst Theor Phys, D-66041 Saarbrucken, Germany

[4] Tech Univ Carolo Wilhelmina Braunschweig, Inst Theor Phys, D-38106 Braunschweig, Germany

[5] Stockholm Univ, Inst Inorgan Chem, S-10601 Stockholm, Sweden

[6] CNRS, CEMES, F-31062 Toulouse, France

[7] Univ Lausanne, Inst Phys Theor, CH-1015 Lausanne, Switzerland

来源：

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS | 2002年 / 63卷 / 6-8期

关键词：

oxides; magnetic properties; phase transitions;

D O I：

10.1016/S0022-3697(02)00056-2

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Low energy Raman scattering of the s = 1/2 spin tetrahedra system Cu2Te2O5Br2 is dominated by an excitation at 18 cm(-1) corresponding to an energy E-S = 0.6Delta, with Delta the spin gap of the compound. For elevated temperatures, this mode shows a soft mode-like decrease in energy pointing to an instability of the system. The isostructural reference system Cu2Te2O5Cl2 with a presumably larger inter-tetrahedra coupling does not show such a low energy mode. Instead its excitation spectrum and thermodynamic properties are compatible with long-range Neel-ordering. We discuss the observed effects in the context of quantum fluctuations and competing ground states. (C) 2002 Elsevier Science Ltd. All rights reserved.

引用

页码：1115 / 1117

页数：3

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[2]

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