A room-temperature ferroelectric semimetal

Abstract

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 WTe2 by means of electrical transport, nanoscale piezoresponse measurements, and first-principles calculations. We show that, despite being a Weyl semimetal, WTe2 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.

Surface band bending in semimetal Td-WTe2

“…14 Ferroelectricity and dipole can be tuned by electrically driven stacking transitions in few-layer WTe 2 . 15 Switchable spontaneous polarization with natural ferroelectric domain structures 16 was also found in WTe 2 bulk, which is polar with non-centro-symmetric structure.…”

“…2b suggest the thickness of oxidation layer is ~ 2.4 nm, agreeing with previous estimation. 16,22 It means the top four WTe 2 layers are nearly oxidized after long time exposure. We must point out that due to the integration of photoelectrons emitting from a depth of d 0 , oxidation ratio obtained from XPS measurements is ~ 19.2%.…”

“…Their DFT calculation suggests polarization is pristine in such polar semimetal due to contribution from ionic cores and valence bands. 16 However, experimental study about the origin of such polarization is still seldom. Normally, out-of-plane spontaneous polarization in single crystal should induce surface charge redistribution and built-in electric elds, which result into band bending near surface.…”

Review on ferroelectric/polar metals

“…Later, Sharma et al demonstrated that WTe2 is a ferroelectric metal even in its bulk form through extensive piezoresponse force microscopy (PFM) measurements ( Fig. 6c-g) 20) .…”

Synthesis and Spectral Investigations of Polymeric Hydrazone Schiff Base and its Transition Metal Complexes with Promising Antimicrobial, Anti-Angeogenic and DNA Photo-Cleavage Activities

“…The coordination behaviour of hydrazones has been well studied and depends on the pH medium, nature of the substituents and also on the position of hydrazone group relative to other moieties. As biologically active compound [7,8] hydrazone find a remarkable application to cure tumor [9], cytotoxic [10], antiproliferative, antibacterial, antiviral, antifungal [11][12][13][14], tuberculosis, leprosy, along with some mental diseases [15][16][17]. Hence many important enzymatic reactions catalyzed by the transition metal complexes take place only due to presence of Schiff bases [18,19].…”