μSR study on the ground state of bond-disordered spin gap system(CH_3)_2CHNH_3Cu(Cl<1-x> Br_x)_3(x=0.95, 0.88)
μSR study on the ground state of bond-disordered spin gap system(CH_3)_2CHNH_3Cu(Cl<1-x> Br_x)_3(x=0.95, 0.88)
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键无序自旋间隙体系(CH_3)_2CHNH_3Cu(Cl<1-x>Br_x)_3(x=0.95, 0.88)基态的μSR研究
DOI：
10.1088/1742-6596/200/2/022011
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
A. Amato
中科院分区：
文献类型：
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作者：
T. Goto;T. Suzuki;S. Nakajima;K. Kanada;T. Saito;A. Oosawa;I. Watanabe;H. Luetkens;A. Amato
宏观测量结果表明，两个自旋能隙系统(CH{sub3}){sub2}CHNH{sub3}Cux{sub3}(X=Cl，Br.)的固溶体在氯含量x在0.44-0.87之间时是无间隙的，否则保持间隙.我们用{u}SR研究了x=0.95和0.88的富氯带隙区域的基态，发现它们在微观上被分成两个组分，即磁性小岛和围绕它们的单线态海。随着温度的降低，孤岛自旋涨落的特征频率明显减慢。然而，自旋涨落谱在1K左右停止，低于1K，自旋涨落谱不再向下变化到15mK。这些结果表明，与存在奇异基态的富溴体系x<；0.44不同，富氯体系x>；0.87仍然是顺磁性的，没有表现出长程有序。这种差异被认为源于霍尔丹间隙对无序的健壮性。
Solid solution of the two spin gap systems (CH{sub 3}){sub 2}CHNH{sub 3}CuX{sub 3} (X=Cl, Br) was reported from results of macroscopic measurements to be gapless when fraction of Cl content x is in between 0.44 and 0.87, and otherwise remains gapped. We have investigated by {mu}SR the ground state of Cl-rich gapped region x=0.95 and 0.88 to find that they are microscopically phase separated into two components, magnetic tiny islands and singlet sea surrounding them. With decreasing temperature, the characteristic frequency of spin fluctuation in islands showed a significant slow down. However, the slow down ceased around 1 K, below which the spin fluctuation spectrum did not change down to 15 mK. These results indicate that unlike the Br-rich system x < 0.44 where appearance of an exotic ground state has been argued, the Cl-rich system x > 0.87 persists to be paramagnetic without showing a long-range order. This difference is considered to be originated in the robustness of Haldane gap against disorder.