Department of Physics, University of California San Diego, La Jolla, CA 92093.
Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA 92093.
Proc Natl Acad Sci U S A. 2021 May 18;118(20). doi: 10.1073/pnas.2026591118.
Electrical resistivity measurements were performed on single crystals of URu Os Si up to = 0.28 under hydrostatic pressure up to = 2 GPa. As the Os concentration, , is increased, 1) the lattice expands, creating an effective negative chemical pressure (); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure is required to induce the HO→LMAFM phase transition. We compare the behavior of the (, ) phase boundary reported here for the URu Os Si system with previous reports of enhanced HO in URuSi upon tuning with or similarly in URu Fe Si upon tuning with positive (). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URuSi We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5-electron and transition metal -electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URuSi Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5-electron states and the -electron states of Ru and its isoelectronic Fe and Os substituents in URuSi.
电阻率测量是在静水压力高达 2 GPa 下对 URu Os Si 单晶进行的， 高达 0.28。随着 Os 浓度 的增加，1）晶格膨胀，产生有效负化学压力（）；2）隐藏序（HO）相增强，系统向大磁矩反铁磁（LMAFM）相驱动；3）诱导 HO→LMAFM 相变所需的外部压力 减少。我们将这里报道的 URu Os Si 系统中（，）相边界的行为与先前报道的 URuSi 中通过调节或类似地在 URu Fe Si 中通过调节正（）增强 HO 的报告进行比较。值得注意的是，压力、Fe 取代和 Os 取代是增强 HO 相并在 URuSi 中诱导一阶到 LMAFM 相变的仅知扰动。我们提出了一种情景，即在压力下施加或 Fe 和 Os 离子的等电子取代 Ru 导致 U-5 电子和过渡金属 -电子态的杂化增加，这导致顺磁相中的电子不稳定性和同时形成 HO（和 LMAFM）在 URuSi 中。包括紧束缚近似计算，以确定 U-5 电子态与 Ru 及其等电子 Fe 和 Os 取代物的 -电子态之间杂化的强度在 URuSi 中。
