No Evidence for “Small-Moment Antiferromagnetism” under Ambient Pressure in URu2Si2: Single-Crystal 29Si NMR Study
No Evidence for “Small-Moment Antiferromagnetism” under Ambient Pressure in URu2Si2: Single-Crystal 29Si NMR Study
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DOI：
10.1143/jpsj.76.033708
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发表时间：
2007-03
影响因子：
1.7
通讯作者：
S. Takagi;S. Ishihara;S. Saitoh;H. Sasaki;H. Tanida;M. Yokoyama;H. Amitsuka
中科院分区：
文献类型：
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作者：
S. Takagi;S. Ishihara;S. Saitoh;H. Sasaki;H. Tanida;M. Yokoyama;H. Amitsuka
对重电子超导体UrU2Si2在外加磁场H Ext∥c轴和环境压力P的作用下，用2 9Si核磁共振研究了T0=17.5K以下的未知隐序(HO)相.对于先前提出的小磁矩反铁磁性(SMAF)模型，其中环境P下的微小反铁磁性(AF)被归因于具有有序矩µSMAF=0.02-0.04µB的空间均匀的AF，线的分裂将基于P诱导的AF中相应的分裂的比例来预期。然而，在T=4.5K时，我们观察到这条线没有分裂。这清楚地表明，SMAF模型不能描述环境-P属性。在T0以下至∼14K，29Si核磁共振谱线在顺磁宽度上表现出额外的展宽。然而，附加贡献在∼14K以下消失，这表明在低温下，Ho本身在沿c轴的29Si位产生的内场几乎为零。
The still unidentified hidden order (HO) phase below T 0 = 17.5 K in the heavy-electron superconductor URu 2 Si 2 has been investigated by 29 Si NMR on a single crystal under external magnetic field H ext ∥ c -axis and ambient pressure P . For a previously proposed model of the small-moment antiferromagnetism (SMAF), in which tiny-moment antiferromagnetism (AF) under ambient P is ascribed to spatially homogeneous AF with an ordered moment µ SMAF = 0.02–0.04 µ B , splitting of the line would be expected on the basis of a scaling from the corresponding splitting in the P -induced AF. However, we observed at T = 4.5 K no splitting of the line. This clearly indicates that the SMAF model cannot describe the ambient- P properties. Below T 0 down to ∼14 K, the 29 Si NMR line shows additional broadening over the paramagnetic width. The additional contribution, however, disappears below ∼14 K, which indicates that the HO itself produces almost zero internal field at the 29 Si site along the c -axis at low temperat...