Department of Physics, Princeton University, Princeton, NJ 08544, USA.
Department of Physics and Astronomy, San José State University, San José, CA 95192, USA.
Science. 2017 Sep 29;357(6358):1385-1388. doi: 10.1126/science.aam7838. Epub 2017 Sep 28.
The interplay of strong interactions and magnetic fields gives rise to unusual forms of superconductivity and magnetism in quantum many-body systems. Here, we present an experimental study of the two-dimensional Fermi-Hubbard model-a paradigm for strongly correlated fermions on a lattice-in the presence of a Zeeman field and varying doping. Using site-resolved measurements, we revealed anisotropic antiferromagnetic correlations, a precursor to long-range canted order. We observed nonmonotonic behavior of the local polarization with doping for strong interactions, which we attribute to the evolution from an antiferromagnetic insulator to a metallic phase. Our results pave the way to experimentally mapping the low-temperature phase diagram of the Fermi-Hubbard model as a function of both doping and spin polarization, for which many open questions remain.
强相互作用和磁场的相互作用导致量子多体系统中出现异常形式的超导性和磁性。在这里，我们对二维费米-哈伯德模型进行了实验研究，该模型是晶格上强关联费米子的范例，存在塞曼场和变化的掺杂。通过局域测量，我们揭示了各向异性反铁磁关联，这是长程倾斜有序的前兆。我们观察到强相互作用下掺杂的局域极化的非单调行为，我们将其归因于从反铁磁绝缘体到金属相的演化。我们的结果为实验绘制费米-哈伯德模型的低温相图作为掺杂和自旋极化的函数铺平了道路，其中仍有许多悬而未决的问题。
