Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1412.8637

Large diameter multiwall nanotubes of MgB2: structural aspects and stability of superconducting nanotubular magnesium boride

P. Banacky·P. Noga·V. Szocs·J. Noga
View original source ↗Read source document ↗Export metadata ↓

Abstract

Based on a theoretical study, we demonstrated that magnesium boride nanotubes can reach the same stability as bulk MgB2 structure. However, most stable nanotubular forms are not structurally derived from mixed triangular-hexagonal structural motifs of a single layer sheet, which is thought to be the 2D precursor form of all boron nanotubes. MgB2 multiwall nanotubular structures that are derived from multilayer MgB2 slabs with honeycomb B-networks in hexagonal lattices are more stable. The results of an ab initio study of multilayer slabs of MgB2 show that a 25-layer slab approaches the stability of bulk MgB2. The critical parameter of the corresponding multiwall nanotubes is the inner diameter; the calculated value is ~ 32.6nm, which is independent of the number of walls. The outer diameters of 25-wall nanotubes are ~ 51 nm, and terminal Mg atoms are located on the outer surfaces of the nanotubes. The electronic band structures of MgB2-multiwall nanotubes (MgB2MWNT) correspond to the band structure character and topology of superconducting bulk MgB2. The results confirm that the quasi-1D superconductor MgB2MWNT is a stable structure and can be synthesized.

Explore related subjects

cond-mat.mes-hallcond-mat.mtrl-scicond-mat.supr-con

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P. Banacky, P. Noga, V. Szocs, J. Noga. 2015-04-10. Large diameter multiwall nanotubes of MgB2: structural aspects and stability of superconducting nanotubular magnesium boride. https://doi.org/10.1002/pssb.201552027

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Inverse Purcell Suppression of Decoherence in Majorana Qubits via Environmental Engineering

We show that the electromagnetic or phononic environment of a topological quantum device can be engineered to actively suppress decoherence. For a Majorana qubit in a superconducting wire, the exponentially small splitting $ε\sim e^{-L/ξ}$ that provides topological protection also makes the qubit vulnerable to low-frequency noise. From a microscopic local interaction, we derive the effective low-energy coupling between the Majorana parity operator and a bosonic field; the coupling strength itself is proportional to $ε$, reflecting the qubit's non-local nature. The resulting pure-dephasing rate scales as $Γ_ϕ\propto ε^2 S(ε)$, with $S(ε)$ the environmental noise power at frequency $ε$. In the experimentally relevant high-temperature regime ($k_B T \gtrsim \hbarε$), this gives $Γ_ϕ\propto ερ(ε) T$, where $ρ(ε)$ is the environmental density of states. By engineering an environment with a suppressed low-frequency density of states, $ρ_{\text{eng}}(ω) = ρ_0 (ω/ω_c)^α$ for $ω< ω_c$ ($α> 0$), the dephasing rate drops to $Γ_ϕ^{\text{eng}} \propto ε^{α+1} \propto e^{-(α+1)L/ξ}$. Thus, longer wires yield exponentially better coherence---a direct synergy with topological protection. This "inverse Purcell" effect, which suppresses the density of states at the qubit frequency, provides a quantitative design principle for environmental engineering. Our work establishes spectral density shaping as a practical method for enhancing coherence in topological quantum devices.

cond-mat.mes-hall↗
arXiv2026

Axionic tunneling from a topological Kondo insulator

Discoveries over the past two decades have revealed the remarkable ability of quantum materials to emulate relativistic properties of the vacuum, from Dirac cones in graphene to Dirac surface states of topological insulators. Yet one of the most elusive consequences of topology in quantum matter -- the axionic ${\bf E}\cdot{\bf B}$ contribution to the electromagnetic response, predicted to produce strong magnetoelectric effects -- remains experimentally challenging to detect. Here we report evidence for an axion-like magnetoelectric response obtained through scanning tunneling microscopy (STM) using a SmB$_6$ nanowire tip on an antiferromagnetic Fe$_{1+x}$Te sample. Our measurements reveal a striking voltage-induced magnetization: millivolt biases generate measurable tip magnetizations that reverse with the voltage. The magnitude, tunability, and reversibility of this signal are consistent with an axion-like ${\bf E} \cdot {\bf B}$ coupling, which naturally accounts for the voltage-odd magnetic component of the tip spectral function while strongly constraining a conventional static-magnetism interpretation. Moreover, millivolt-scale control of spin polarization in a tunnel junction provides a new route for probing axionic electrodynamics and opens avenues for future STM and spintronic applications.

cond-mat.mes-hall↗
arXiv2026

Exciton-mediated optical control of liquid-solid friction

Interfacial friction in nanofluidic systems can arise from fluctuation-induced coupling between liquid charge fluctuations and the internal excitations of the confining solid. Here, we develop a microscopic theory of exciton-mediated solid-liquid friction based on the coupling between optically generated excitons and charge fluctuations in water. We distinguish between static excitons, localized by disorder or functionalization, and dynamic excitons, which interact with water through polarization fluctuations. In both cases, we derive analytical formulas for the excitonic friction, which is experimentally tunable and can significantly reduce the slip length and thereby the hydraulic permeability of nanochannels. Applying our framework to carbon nanotubes, we quantitatively reproduce the recent measurements of Kistwal et al., showing a reduction of nanotube diffusion under optical excitation, without fitting parameters. More broadly, our results establish excitons as a mechanism to optically control nanofluidic transport and suggest that excitonic photoluminescence could provide an optical probe of flow velocity inside nanochannels.

cond-mat.mes-hall↗