Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, 13083-859 Campinas, SP, Brazil and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Phys Rev Lett. 2014 Jun 13;112(23):236401. doi: 10.1103/PhysRevLett.112.236401. Epub 2014 Jun 10.
Very high field (29)Si-NMR measurements using a fully (29)Si-enriched URu(2)Si(2) single crystal were carried out in order to microscopically investigate the "hidden order" (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the (29)Si shift, (29)K(c). Moreover, a strong enhancement of (29)K(c) develops near a critical field H(c) ≃ 35.6 T, and the ^{29}Si-NMR signal disappears suddenly at H(c), indicating the total suppression of the HO state. Nevertheless, a weak and shifted (29)Si-NMR signal reappears for fields higher than H(c) at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.
采用完全（29）Si 富集的 URu（2）Si（2）单晶进行了超高场（29）Si-NMR 测量，以便在高场极限下微观研究“隐藏序”（HO）态和相邻的磁相。在测量的最低温度为 0.4 K 时，通过（29）Si 位移（29）K（c）检测到在 HO 态内接近 22 T 的费米表面不稳定性的明显异常。此外，在临界场 H（c）≈35.6 T 附近，（29）K（c）强烈增强，并且在 H（c）处（29）Si-NMR 信号突然消失，表明 HO 态的完全抑制。然而，在 4.2 K 时，高于 H（c）的磁场中再次出现微弱且偏移的（29）Si-NMR 信号，这为铀有序矩的各向异性引起的磁相内的磁结构提供了证据。
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