Do you want to publish a course? Click here

Turning ZrTe5 into semiconductor through atomic intercalation

167   0   0.0 ( 0 )
 Added by Shao-Chun Li
 Publication date 2019
  fields Physics
and research's language is English




Ask ChatGPT about the research

In this work, we use the liquid ammonia method to successfully intercalate potassium atoms into ZrTe5 single crystal, and find a transition from semimetal to semiconductor at low temperature in the intercalated ZrTe5. The resistance anomalous peak is gradually suppressed and finally disappears with increasing potassium concentration. Whilst, the according sign reversal is always observed in the Hall resistance measurement. We tentatively attribute the semimetal-semiconductor transition to the lattice expansion induced by atomic intercalation and thereby a larger energy band gap.



rate research

Read More

We report on a general principle using the interlayer exchange coupling to extend the regime of chiral magnetic films in which stable or metastable magnetic skyrmions can appear at zero magnetic field. We verify this concept on the basis of a first-principles model for a Mn monolayer on W(001) substrate, a prototype chiral magnet for which the atomic-scale magnetic texture is determined by the frustration of exchange interactions, impossible to unwind by laboratory magnetic fields. By means of textit{ab initio} calculations for the Mn/W$_m$/Co$_n$/Pt/W(001) multilayer system we show that for certain thicknesses $m$ of the W spacer and $n$ of the Co reference layer, the effective field of the reference layer fully substitutes the required magnetic field for skyrmion formation.
Oxygen was electrochemically intercalated into Sr$_2$IrO$_4$ sintered samples, single crystals and a thin film. We estimate the diffusion length to a few $mu$m and the concentration of the intercalated oxygen to $delta$ $simeq$ 0.01. The latter is thus much smaller than for the cuprate and nickelate parent compounds, for which $delta$ $>$ 0.1 is obtained, which could be a consequence of larger steric effects. The influence of the oxygen doping state on resistivity is small, indicating also a poor charge transfer to the conduction band. It is shown that electrochemical intercalation of oxygen may also contribute to doping, when gating thin films with ionic liquid in the presence of water.
For a wider adoption of electromobility, the market calls for fast-charging, safe, long-lasting batteries with sufficient performance. This drives the exploration of new energy storage materials, and also promotes fundamental investigations of materials already widely used. At the moment, renewed interest in anode materials is observed -- with a particular focus on graphite electrodes for lithium-ion batteries. Here, we focus on the upper limit of lithium intercalation in the morphologically quasi-ideal Highly Oriented Pyrolytic Graphite (HOPG). The state and long-term stability of a sample prepared by immersion of an HOPG crystal in liquid lithium metal at ambient pressure is investigated by static $^7$Li nuclear magnetic resonance (NMR). We resolved signatures of superdense intercalation compounds, LiC$_{6-x}$ with $x>0$, which are monitored upon calendaric ageing. {em Ab initio} thermodynamics and {em ab initio} molecular dynamics reveal the relative stabilities and kinetics of different superdense configurations, providing leads for the interpretation of the NMR results. Including these superdense structures in the conceptual design of high-energy, fast-charge electrodes might provide further insights on the failure mechanisms and performance of Li-ion batteries.
Various bandstructure engineering methods have been studied to improve the performance of graphitic transparent conductors; however none demonstrated an increase of optical transmittance in the visible range. Here we measure in situ optical transmittance spectra and electrical transport properties of ultrathin-graphite (3-60 graphene layers) simultaneously via electrochemical lithiation/delithiation. Upon intercalation we observe an increase of both optical transmittance (up to twofold) and electrical conductivity (up to two orders of magnitude), strikingly different from other materials. Transmission as high as 91.7% with a sheet resistance of 3.0 {Omega} per square is achieved for 19-layer LiC6, which corresponds to a figure of merit {sigma}_dc/{sigma}_opt = 1400, significantly higher than any other continuous transparent electrodes. The unconventional modification of ultrathin-graphite optoelectronic properties is explained by the suppression of interband optical transitions and a small intraband Drude conductivity near the interband edge. Our techniques enable the investigation of other aspects of intercalation in nanostructures.
Cr2Ge2Te6 is an intrinsic ferromagnetic semiconductor with van der Waals type layered structure, thus represents a promising material for novel electronic and spintronic devices. Here we combine scanning tunneling microscopy and first-principles calculations to investigate the electronic structure of Cr2Ge2Te6. Tunneling spectroscopy reveals a surprising large energy level shift and change of energy gap size across the ferromagnetic to paramagnetic phase transition, as well as a peculiar double-peak electronic state on the Cr-site defect. These features can be quantitatively explained by density functional theory calculations, which uncover a close relationship between the electronic structure and magnetic order. These findings shed important new lights on the microscopic electronic structure and origin of magnetic order in Cr2Ge2Te6.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا