Spin gap behavior in ladder-type of quasi-one-dimensional spin (S=1/2) system SrCu2O3
Spin gap behavior in ladder-type of quasi-one-dimensional spin (S=1/2) system SrCu2O3
复制标题
梯型准一维自旋(S=1/2)体系SrCu2O3中的自旋间隙行为
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
M. Takano
中科院分区：
文献类型：
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作者：
K. Ishida;Y. Kitaoka;K. Asayama;M. Azuma;Z. Hiroi;M. Takano
用Cu NMR研究了自旋S =1/2的两条腿梯形体系SrCu 2 O3的低能自旋激发.在100-300 K的T范围内，由于核自旋晶格弛豫速率1/T1的活化降低，自旋能隙Δ打开，其值为680 K，这与理论值Δ φ 0.5 J =650 K定量一致，如果使用与正方形晶格系统中相同的1300 K值作为反铁磁交换耦合常数J。从自旋回波衰减率1/T2 G的测量进一步推导出，磁相干长度λ/ a（a：沿链沿着Cu原子间的晶格间距）保持有限，（λ/ a）λ 13，与La 2CuO 4在TN附近的值相当。因此，这类铜酸盐是具有自旋能隙的受抑量子反铁磁体（AF）。
Low-energy spin excitation in a spin S =1/2 two-leg ladder system SrCu 2 O 3 has been investigated by Cu NMR. From an activated decrease of the nuclear-spin lattice relaxation rate, 1/ T 1 , in a T -range of 100–300 K, a spin gap, Δ, is demonstrated to open with a value of 680 K, which is in quantitative agreement with the theoretical value of Δ∼0.5 J =650 K , if the same value of 1300 K as in the square lattice system is used as the antiferromagnetic exchange coupling constant, J . It is furthermore deduced from the measurement of the spin-echo decay rate, 1/ T 2G , that a magnetic coherence length, ξ/ a ( a : lattice spacing between Cu atoms along the chain), remains finite with (ξ/ a )∼13, comparable to a value in La 2 CuO 4 near T N . This class of cuprate is thus a frustrated quntum antiferromagnet (AF) with a spin gap.