Sharma Pankaj, Xiang Fei-Xiang, Shao Ding-Fu, Zhang Dawei, Tsymbal Evgeny Y, Hamilton Alex R, Seidel Jan
School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of New South Wales, Sydney, NSW 2052, Australia.
Sci Adv. 2019 Jul 5;5(7):eaax5080. doi: 10.1126/sciadv.aax5080. eCollection 2019 Jul.
Coexistence of reversible polar distortions and metallicity leading to a ferroelectric metal, first suggested by Anderson and Blount in 1965, has so far remained elusive. Electrically switchable intrinsic electric polarization, together with the direct observation of ferroelectric domains, has not yet been realized in a bulk crystalline metal, although incomplete screening by mobile conduction charges should, in principle, be possible. Here, we provide evidence that native metallicity and ferroelectricity coexist in bulk crystalline van der Waals WTe by means of electrical transport, nanoscale piezoresponse measurements, and first-principles calculations. We show that, despite being a Weyl semimetal, WTe has switchable spontaneous polarization and a natural ferroelectric domain structure at room temperature. This new class of materials has tantalizing potential for functional nanoelectronics applications.
1965年由安德森和布朗特首次提出的可逆极性畸变与金属性共存从而产生铁电金属的现象，至今仍难以捉摸。尽管原则上移动传导电荷的不完全屏蔽是可能的，但在块状晶体金属中尚未实现电可切换的本征极化以及铁电畴的直接观测。在此，我们通过电输运、纳米级压阻响应测量和第一性原理计算，提供了块状晶体范德华WTe中本征金属性和铁电性共存的证据。我们表明，尽管WTe是一种外尔半金属，但在室温下它具有可切换的自发极化和天然的铁电畴结构。这类新型材料在功能性纳米电子应用方面具有诱人的潜力。
