اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدImage potential states as quantum probe of graphene interfaces
139
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Image potential states (IPSs) are electronic states localized in front of a surface in a potential well formed by the surface projected bulk band gap on one side and the image potential barrier on the other. In the limit of a two-dimensional solid a double Rydberg series of IPSs has been predicted which is in contrast to a single series present in three-dimensional solids. Here, we confirm this prediction experimentally for mono- and bilayer graphene. The IPSs of epitaxial graphene on SiC are measured by scanning tunnelling spectroscopy and the results are compared to ab-initio band structure calculations. Despite the presence of the substrate, both calculations and experimental measurements show that the first pair of the double series of IPSs survives, and eventually evolves into a single series for graphite. Thus, IPSs provide an elegant quantum probe of the interfacial coupling in graphene systems.
قيم البحث
اقرأ أيضاً
We explore the dependence of electrical transport in a graphene field effect transistor (GraFET) on the flow of the liquid within the immediate vicinity of that transistor. We find large and reproducible shifts in the charge neutrality point of GraFE
Ts that are dependent on the fluid velocity and the ionic concentration. We show that these shifts are consistent with the variation of the local electrochemical potential of the liquid next to graphene that are caused by the fluid flow (streaming potential). Furthermore, we utilize the sensitivity of electrical transport in GraFETs to the parameters of the fluid flow to demonstrate graphene-based mass flow and ionic concentration sensing. We successfully detect a flow as small as~70nL/min, and detect a change in the ionic concentration as small as ~40nM.
We use the charged tip of a low temperature scanning probe microscope to perturb the transport through a graphene nanoconstriction. Maps of the conductance as a function of tip position display concentric halos, and by following the expansion of the
halos with back-gate voltage we are able to identify an elongated domain over the nanoconstriction where they originate. Amplitude modulations of the transmission resonances are correlated with the gradient of the tip-induced potential and we analyze this in terms of modified coupling between localized states.
Photo-induced edge states in low dimensional materials have attracted considerable attention due to the tunability of topological properties and dispersion. Specifically, graphene nanoribbons have been predicted to host chiral edge modes upon irradia
tion with circularly polarized light. Here, we present numerical calculations of time-resolved angle resolved photoemission spectroscopy (trARPES) and time-resolved resonant inelastic x-ray scattering (trRIXS) of a graphene nanoribbon. We characterize pump-probe spectroscopic signatures of photo-induced edge states, illustrate the origin of distinct spectral features that arise from Floquet topological edge modes, and investigate the roles of incoming photon energies and finite core-hole lifetime in RIXS. With momentum, energy, and time resolution, pump-probe spectroscopies can play an important role in understanding the behavior of photo-induced topological states of matter.
The energies of valley-orbit states in silicon quantum dots are determined by an as yet poorly understood interplay between interface roughness, orbital confinement, and electron interactions. Here, we report measurements of one- and two-electron val
ley-orbit state energies as the dot potential is modified by changing gate voltages, and we calculate these same energies using full configuration interaction calculations. The results enable an understanding of the interplay between the physical contributions and enable a new probe of the quantum well interface.
Quantum-confined electronic states such as quantum-well states (QWS) inside thin Pb(111) films and modified image-potential states (IPS) above the Pb(111) films grown on Si(111)7$times$7 substrate were studied by means of low-temperature scanning tun
nelling microscopy (STM) and spectroscopy (STS) in the regime of constant current $I$. By plotting the position of the $n-$th emission resonances $U^{,}_n$ versus $n^{2/3}$ and extrapolating the linear fit for the dependence $U^{,}_n(n^{2/3})$ in the high-$n$ limit towards $n=0$, we estimate the local work function for the Pb(111) film: $Wsimeq 3.8pm 0.1,$eV. We experimentally demonstrate that modifications of the shape of the STM tip can change the number of the emission peaks associated with the resonant tunnelling via quantized IPS levels for the same Pb terrace; however it does not affect the estimate of the local work function for the flat Pb terraces. We observe that the maxima in the spectra of the differential tunnelling conductance $dI/dU$ related to both the QWS and the modified IPS resonances are less pronounced if the STM tip becomes more blunt.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
