The devil's staircase in 1-dimensional dipolar Bose gases in optical lattices
F. J. Burnell
备注：
Chapter of doctoral thesis `On Exotic Orders in Strongly Correlated Systems' (Princeton University, 09/09). This presents a more detailed version of [PRB 80: 174519 (2009)] (arXiv:0901.4366)
我们考虑一个单组分气体的偶极玻色子限制在一个一维的光晶格，其中的偶极子是对齐的，使得长程偶极相互作用是最大的排斥。在零站点间跳跃和足够大的现场相互作用的限制下，相图是一个完整的魔鬼的楼梯填充分数在0和1之间：每个相称的状态在一个合理的填充是稳定的，在有限的化学势的间隔，并为每个化学势的系统是在一个缺口相称的阶段。我们扰动远离这个限制在两个实验动机的方向，涉及到增加跳跃和减少现场相互作用。除了跳跃单独产生一个相图，我们计算在微扰理论中的跳跃，相称的莫特阶段现在竞争的超流体。我们通过玻色化捕获了Mott超流相变的物理过程。在一个有限的陷阱，我们认为，使用LDA和模拟退火，这导致在区域的相称状态与占主导地位的超流相关补丁分开。进一步软化的现场相互作用产生替代相称的国家与双occupancy，可以形成自己的魔鬼的楼梯，我们描述这些国家，并讨论它们之间可能的过渡。在这种情况下，增加一个跳跃项会产生一维的“超固体”，它同时表现出离散的对称性破缺和超流性。这项工作的内容首次作为博士论文“On Exotic Orders in Strongly Correlated Systems”（普林斯顿大学，09/09，由S. L. Sondhi），并且构成[PRB 80：174519（2009）]的相当详细的版本。
英文摘要：
We consider a single-component gas of dipolar bosons confined in a one-dimensional optical lattice, where the dipoles are aligned such that the long-ranged dipolar interactions are maximally repulsive. In the limit of zero inter-site hopping and sufficiently large on-site interaction, the phase diagram is a complete devil's staircase for filling fractions between 0 and 1: every commensurate state at a rational filling is stable over a finite interval in chemical potential, and for every chemical potential the system is in a gapped commensurate phase. We perturb away from this limit in two experimentally motivated directions involving the addition of hopping and a reduction of the onsite interaction. The addition of hopping alone yields a phase diagram, which we compute in perturbation theory in the hopping, where the commensurate Mott phases now compete with the superfluid. We capture the physics of the Mott-superfluid phase transitions via bosonization. In a finite trap, we argue using an LDA and simulated annealing that this results in regions of commensurate states separated by patches with dominant superfluid correlations. Further softening of the onsite interaction yields alternative commensurate states with double occupancies which can form a devil's staircase of their own; we describe these states and discuss the possible transitions between them. Adding a hopping term in this case produces one-dimensional "supersolids" which simultaneously exhibit discrete broken symmetries and superfluidity. The contents of this work was first published as a chapter in the doctoral thesis `On Exotic Orders in Strongly Correlated Systems' (Princeton University, 09/09, supervised by S. L. Sondhi), and constitutes a considerably more detailed version of [PRB 80: 174519 (2009)].
Observation of Devil's Staircase in the Novel Spin Valve System SrCo$_6$O$_{11}$
利用共振软X射线散射作为温度和磁场的函数，我们揭示了大量的几乎简并磁序SrCo 6 O 11。这种受抑材料中的类伊辛自旋实际上展示了所谓的磁性魔鬼楼梯。它演示了如何一个磁场诱导不同的微观自旋配置之间的转变，这是负责的SrCo 6 O 11的磁阻。因此，这种材料构成了一个独特的磁魔鬼的楼梯和自旋阀效应的组合，产生一种新型的磁阻系统。
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Instituto de Física Gleb Wataghin, UNICAMP（坎皮纳斯大学格莱布·瓦塔金物理研究所）；PSI Center for Neutron and Muon Sciences CNM（瑞士保罗谢尔研究所中子与μ子科学中心）；Neutron Scattering Division, Oak Ridge National Laboratory（橡树岭国家实验室中子散射部）；Centro Brasileiro de Pesquisas Física（巴西物理研究中心）；Physik-Institut, Universität Zürich（苏黎世大学物理学院）
