Continuous Mott transition in semiconductor moire superlattices
Continuous Mott transition in semiconductor moire superlattices
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DOI：
10.1038/s41586-021-03853-0
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发表时间：
2021-09-16
期刊：
影响因子：
64.8
通讯作者：
Mak, Kin Fai
中科院分区：
文献类型：
--
作者：
Li, Tingxin;Jiang, Shengwei;Mak, Kin Fai
随着电子相互作用的增加，朗道费米液体演变成非磁性莫特绝缘体是物理学中最令人困惑的量子相变之一（1-6）。跃迁附近被认为是物质的奇异状态，如量子自旋液体（4-7），激子凝聚（8）和非常规超导（1）。半导体莫尔条纹材料在三角形晶格上实现了高度可控的哈伯德模型模拟器（9-22），提供了通过电子相互作用的连续调谐来驱动金属-绝缘体转变（MIT）的独特机会。在这里，通过电调谐MoTe 2/WSe 2莫尔超晶格中的有效相互作用强度，我们观察到一个连续的MIT在一个固定的填充每个单元格的一个电子。量子临界性的存在是支持的缩放崩溃的电阻，不断消失的电荷间隙作为临界点接近从绝缘侧，和发散的准粒子有效质量从金属侧。我们还观察到一个平滑的演变的磁化率在整个MIT和没有证据的长程磁序下降到类似的居里-外斯温度的5%。这表明在绝缘侧存在大量的低能自旋激发，这一点被在金属侧观察到的Pomeranchuk效应进一步证实。我们的结果与二维连续Mott转变的普适临界理论一致（4，23）。莫尔超晶格中的相互作用强度被调谐为在固定的电子密度下驱动连续的金属-绝缘体转变。
The evolution of a Landau Fermi liquid into a non-magnetic Mott insulator with increasing electronic interactions is one of the most puzzling quantum phase transitions in physics(1-6). The vicinity of the transition is believed to host exotic states of matter such as quantum spin liquids(4-7), exciton condensates(8) and unconventional superconductivity(1). Semiconductor moire materials realize a highly controllable Hubbard model simulator on a triangular lattice(9-22), providing a unique opportunity to drive a metal-insulator transition (MIT) via continuous tuning of the electronic interactions. Here, by electrically tuning the effective interaction strength in MoTe2/WSe2 moire superlattices, we observe a continuous MIT at a fixed filling of one electron per unit cell. The existence of quantum criticality is supported by the scaling collapse of the resistance, a continuously vanishing charge gap as the critical point is approached from the insulating side, and a diverging quasiparticle effective mass from the metallic side. We also observe a smooth evolution of the magnetic susceptibility across the MIT and no evidence of long-range magnetic order down to similar to 5% of the Curie-Weiss temperature. This signals an abundance of low-energy spinful excitations on the insulating side that is further corroborated by the Pomeranchuk effect observed on the metallic side. Our results are consistent with the universal critical theory of a continuous Mott transition in two dimensions(4,23).The interaction strength in moire superlattices is tuned to drive a continuous metal-to-insulator transition at a fixed electron density.