Hydrostatic pressure response of an oxide two-dimensional electron system
J. Zabaleta, V. S. Borisov, R. Wanke, H. O. Jeschke, S. C. Parks, B. Baum, A. Teker, T. Harada, K. Syassen, T. Kopp, N. Pavlenko, R. Valentí, J. Mannhart
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13 pages and 10 figures main text. 6 pages and 10 figures supplementary information. Phys Rev B (in press)
Two-dimensional electron systems with fascinating properties exist in multilayers of standard semiconductors, on helium surfaces, and in oxides. Compared to the two-dimensional (2D) electron gases of semiconductors, the 2D electron systems in oxides are typically more strongly correlated and more sensitive to the microscopic structure of the hosting lattice. This sensitivity suggests that the oxide 2D systems are highly tunable by hydrostatic pressure. Here we explore the effects of hydrostatic pressure on the well-characterized 2D electron system formed at LaAlO$_{3}$ -SrTiO$_{3}$ interfaces[1] and measure a pronounced, unexpected response. Pressure of $\sim$2 GPa reversibly doubles the 2D carrier density $n_{s}$ at 4 K. Along with the increase of $n_{s}$, the conductivity and mobility are reduced under pressure. First-principles pressure simulations reveal the same behavior of the carrier density and suggest a possible mechanism of the mobility reduction, based on the dielectric properties of both materials and their variation under external pressure.
Effects of hydrostatic pressure on the magnetic susceptibility of ruthenium oxide Sr3Ru2O7: Evidence for pressure-enhanced antiferromagnetic instability
Chemical- and hydrostatic-pressure effects on the Kitaev honeycomb material Na$_2$IrO$_3$
利用μ子自旋弛豫和核磁共振方法研究了量子自旋液体态的候选材料\tcr{polycrystalline} Na $_2$ IrO $_3$在化学压力和流体静压下的低温磁性. Li对Na的化学取代促进了非均匀磁有序，而流体静压（高达3.9GPa）导致有序温度$T_\mathrm{N}$的提高.在第一种情况下，不均匀的磁序表明广泛分布的$j=\,$ \textonehalf \ Ir $^{4+}$磁矩的短程或长程相关性，反映了局部无序。在施加压力点下$T_\mathrm{N}$的增加是由于层间压缩引起的三维相互作用的强度增加。
Stabilization of antiferromagnetism in CeFe2 alloys: Effects of chemical and hydrostatic pressure
研究了CeFe_2中Al、Mn和Sb掺杂的影响以及压力的影响。Al掺杂引起了FM-AFM转变和磁矩和TC值的降低，清楚地表明AFM组分的生长。Mn和Sb掺杂仅引起TC值的降低。研究发现，在一般情况下，外部压力增强的反铁磁性在纯和掺杂的合金。Ce 4f- Fe 3d杂化的增强和外加压力的作用可能是这些合金反铁磁性稳定的原因。
Crossover from impurity-induced ordered phase to uniform antiferromagnetic phase under hydrostatic pressure in the doped spin-gap system TlCu$_{1-x}$Mg$_x$Cl$_3$
Electron-phonon coupling in EuAl4 under hydrostatic pressure
University of Augsburg（奥格斯堡大学）；Technische Universität Dresden（德累斯顿工业大学）；Donostia International Physics Center (DIPC)（圣塞巴斯蒂安国际物理中心）；Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences（俄罗斯科学院西伯利亚分院基列斯基物理研究所）；Rice University（莱斯大学）；Princeton University（普林斯顿大学）
Separation of energy scales in undoped YbRh$_2$Si$_2$ under hydrostatic pressure
通过低$T$磁化强度测量，研究了YbRh $_2$ Si $_2$在量子临界点附近的温度（$T$）-磁场（$H$）相图.我们的分析表明，能量标度$T^\star(H)$，以前与近藤击穿和终止于0.06 T的$T\to 0$，保持不变的压力下，而反铁磁临界场从0.06 T（$p=0$）增加到0.29 T（$p=1.28$ GPa），导致在交叉的$T_N(H)$和$T^\star(H)$。我们的结果与Yb（Rh $_{1-x}$ Co $_x$）$_2$ Si $_2$上的结果非常相似，证明了Co诱导的无序不是化学压力下两种尺度脱离的原因.
The honeycomb antiferromagnet BaCo2(AsO4)2, in which small in-plane magnetic fields (H1 = 0.26 T and H2 = 0.52 T at T = 1.8 K < TN = 5.4 K) induce two magnetic phase transitions, has attracted attention as a possible candidate material for the realization of Kitaev physics based on the 3d element Co2+. Here, we report on the change of the transition temperature TN and the critical fields H1 and H2 of BaCo2(AsO4)2 with hydrostatic pressure up to ~ 20 kbar, as determined from magnetization and specific heat measurements. Within this pressure range, a marginal increase of the magnetic ordering te…
Hydrostatic pressure effects on the static magnetism in Eu(Fe$_{0.925}$Co$_{0.075}$)$_{2}$As$_{2}$
用互补电阻率、交流磁化率和单晶中子衍射测量研究了流体静压对Eu（Fe $_{0.925}$ Co $_{0.075}$）$_{2}$ As $_{2}$静态磁性的影响。建立了Eu（Fe $_{0.925}$ Co $_{0.075}$）$_{2}$ As $_{2}$的压温相图。结构相变以及Fe亚晶格的自旋密度波序随着压力的增加而逐渐被抑制，并在2.0 GPa以上完全消失。与此相反，Eu亚晶格的磁序持续在整个研究的压力范围高达14 GPa，但显示出非单调的变化与压力。随着静水压力的增加，Eu的磁态从基态的倾斜反铁磁结构，经过中压下的纯铁磁结构，最后演变为高压下可能的“新型”反铁磁结构。在2GPa附近，Eu的强铁磁性与压致超导电性共存。Eu（Fe $_{0.925}$ Co $_{0.075}$）$_{2}$ As $_{2}$中Eu的磁态在静水压作用下的变化可能是由于外压对Eu $^{2+}$磁矩的间接Ruderman-Kittel-Kasuya-Yosida（RKKY）相互作用的影响。
Effect of Hydrostatic Pressure on the Superconductivity in NaxCoO2.yH2O
The effect of hydrostatic pressure on the superconducting transition temperature of Na{0.35}CoO{2}.yH{2}O was investigated by ac susceptibility measurements up to 1.6 GPa. The pressure coefficient of T{c} is negative and the dependence T{c}(p) is nonlinear over the pressure range investigated. The magnitude of the average dlnT{c}/dp=-0.07 GPa^{-1} is comparable to the pressure coefficient of electron-doped high-T{c} copper oxide superconductors with a similar value of T{c}. Our results provide support to the assumption of two-dimensional superconductivity in Na{0.35}CoO{2}.yH{2}O, which is sim…
Robust block magnetism in the spin ladder compound BaFe$_2$Se$_3$ under hydrostatic pressure
大多数铁基超导体（FeSC）具有二维正方形晶格结构。最近的报道中的压力诱导超导自旋梯系统，BaFe $_2$ X $_3$（X =S，Se），介绍了准一维原型和绝缘母体化合物的FeSC。在这里，我们报告的X射线，中子衍射和μ子自旋弛豫实验BaFe $_2$ Se $_3$在静水压力下，调查其磁和结构特性的压力-温度相图。在3.7（3）GPa的压力下发现了结构相变。在6.8（3）GPa和120 K下的中子衍射测量表明，即使在这些高压下，块体磁性仍然存在。磁转变温度$T\rm_N$的稳定增加和随后的快速下降以及压力$P_s$以上的力矩的大大减小表明在该梯形系统中接近超导相的潜在的富相和竞争相。
Comparison of the normal state properties of $κ$-(BEDT-TTF)$_2$Cu(NCS)$_2$ and its deuterated analogue in high magnetic fields and under high hydrostatic pressures
Rapid Suppression of the Charge Density Wave in YBa$_2$Cu$_3$O$_{6.6}$ under Hydrostatic Pressure
我们报告的影响，流体静压（HP）上观察到的电荷密度波在欠掺杂的铜酸盐。用高分辨非弹性X射线散射（IXS）研究了$_2$ O $_{6.6}$（$T_c$ =61 K），揭示了与电荷密度波（CDW）阶相关的声子异常对HP的极端敏感性.正常态展宽和超导诱导的声子软化在Q $_{CDW}$的振幅迅速下降，作为HP的应用，导致在低于$\sim$ 1 GPa的CDW的签名的完全抑制。对YBa $_2$ Cu $_3$ O $_{6.75}$的附加IXS测量表明，这种非常快速的效应不能用压力引起的掺杂水平的修改来解释，并且突出了外部压力和掺杂在调整铜酸盐相图中的不同作用。我们的研究结果提供了新的见解CDW的形成及其与超导性的相互作用的机制。
