Unstable spin-ice order in the stuffed metallic pyrochlore Pr2+xIr2-xO7-delta
Unstable spin-ice order in the stuffed metallic pyrochlore Pr2+xIr2-xO7-delta
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填充金属烧绿石 Pr2 xIr2-xO7-delta 中不稳定的自旋冰顺序
DOI：
10.1103/physrevb.92.054432
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发表时间：
2015
影响因子：
3.7
通讯作者：
Sakakibara Toshiro
中科院分区：
文献类型：
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作者：
MacLaughlin D. E.;Bernal O. O.;Shu Lei;Ishikawa Jun;Matsumoto Yosuke;Wen J. -J.;Mourigal M.;Stock C.;Ehlers G.;Broholm C. L.;Machida Yo;Kimura Kenta;Nakatsuji Satoru;Shimura Yasuyuki;Sakakibara Toshiro
比热，弹性中子散射和μ子自旋旋转实验已经进行了良好的表征样品的“填充”（Pr丰富）。弹性中子散射表明，长程自旋冰“2-in/2-out”磁序在K时开始，在低温时有一个有序的磁矩。在有序态下，关联长度和关联时间的近似下限分别为170 μ T和0.7 ns，实验得到μ子位置上的局域场上限为2.6（7）mT，这比长程自旋-冰矩序的预期偶极场（120-270 mT，取决于μ子位置）小近两个数量级。这种不足部分是由于分裂的非Kramers晶体场基态的近场激子的诱导晶格畸变的双峰。然而，要使这成为唯一的效应，必须抑制Pr矩到λ的距离。另一种情况下，这是与所观察到的减少核超精细肖特基异常的比热一致，调用缓慢的相关Pr矩波动的有序状态，平均的时间尺度上，但静态的时间尺度上的弹性中子散射实验。在这幅图中，μ介子的动态弛豫表明了几纳秒的相关时间，这在中子自旋回波实验中应该是可以观察到的。
Specific heat, elastic neutron scattering, and muon spin rotationexperiments have been carried out on a well-characterized sample of “stuffed” (Pr-rich). Elastic neutron scattering shows the onset of long-range spin-ice “2-in/2-out” magnetic order atK, with an ordered moment ofion at low temperatures. Approximate lower bounds on the correlation length and correlation time in the ordered state are 170 Å and 0.7 ns, respectively.experiments yield an upper bound 2.6(7) mT on the local fieldat the muon site, which is nearly two orders of magnitude smaller than the expected dipolar field for long-range spin-ice ordering ofmoments (120–270 mT, depending on muon site). This shortfall is due in part to splitting of the non-Kramers crystal-field ground-state doublets of near-neighborions by the-induced lattice distortion. For this to be the only effect, however,Pr moments out to a distance ofÅ must be suppressed. An alternative scenario, which is consistent with the observed reduced nuclear hyperfine Schottky anomaly in the specific heat, invokes slow correlated Pr-moment fluctuations in the ordered state that averageon thetime scale, but are static on the time scale of the elastic neutron scattering experiments. In this picture, the dynamic muon relaxation suggests acorrelation time of a few nanoseconds, which should be observable in a neutron spin echo experiment.